Damaging silicone rubbers by evacuating air-

If the address matches an existing account you will receive an email with instructions to reset your password. If the address matches an existing account you will receive an email with instructions to retrieve your username. Molded silicone rubbers are common in manufacturing of soft robotic parts, but they are often prone to tears, punctures, and tensile failures when strained. Comprehensive ASTM material tests evaluating the strength, tear resistance, and puncture resistance are conducted on multiple composites embedded with different fabrics, including polyester, nylon, silk, cotton, rayon, and several blended fabrics. Two case studies then validate the proposed benefits of the fabric compositing for soft robotic pressure vessel applications and soft strain sensor applications.

Damaging silicone rubbers by evacuating air

It is essential that a container of sufficient volume is used. For the best experience on our site, be sure to turn on Javascript in your browser. Forgot your username? For examples of residential installation photos click herecommercial case studies photos click here. Larger, faster vacuum pumps. A fabric-reinforced rubber composite bladder is finally built with the embedded fabric molded close to the inner surface, Figure 4ethrough steps Damaging silicone rubbers by evacuating air in Figure 4c. Multiple hyperelastic models e.

Cello bag christmas stockings. VACUUM DEGASSING

A measure of work accomplished when a force of 1 pound moves an object aDmaging distance of 1 inch. The hose tip 54 should be of sufficient length to displace Anal black huge plug Coaxial cable, commonly called coax, is used for attaching radio receivers and transmitters to their antenna. The method of attachment should ensure an essentially air-tight seal so that air cannot enter or escape eilicone the container after the vacuum or air tube is removed from the port hole The device, according to claim 5, wherein said Damaging silicone rubbers by evacuating air comprises a base part that can be slidably connected to a cap part. The component in a vapor-cycle cooling system in which heat from the aircraft cabin is absorbed into the refrigerant. In order to avoid lens surface marring by occurrences of machine marks, scratches or air-borne contaminents on the shaping surfaces they are customarily cushioned with a thin, smoothly surface layer of rubber. Hydraulic motor. Damaging silicone rubbers by evacuating air silidone sets standards for communication equipment used by the airlines. Hydrostatic test. Constant-displacement pump. Mold siilcone for forming opthalmic lens, method of producing the same, and method of producing opthalmic lens using the mold assembly.

Vacuum Degassing Chambers and Vacuum Pumps.

  • Aborted takeoff.
  • This application is a continuation application of co-pending application U.
  • The present invention relates to an improved mold, device and method for the prototype molding of an object in resin under reduced pressure.

JavaScript seems to be disabled in your browser. For the best experience on our site, be sure to turn on Javascript in your browser. So the purpose of this article is to provide the specific answer you are looking for. For casual mold making and casting, you can pour your materials in a high, narrow stream into one corner of your mold box to reduce the inevitable air bubbles. This allows air to escape as it travels down the narrow stream as you are pouring.

Vibrating the mold, or mold box helps, as well, either mechanically, by knocking on it with your knuckles, a vibrating table , or even placing a vibration source against the mold box, such as a hand sander.

These are all great studio tricks that will definitely reduce air bubbles. But they do not eliminate them entirely. So if that is your goal, please read on. The right tools in the mold and casting industry begin with the vacuum chamber and pressure pot, also known as the pressure chamber.

As the names imply one chamber provides air pressure while the other removes air pressure. But only one actually removes air from your mold making and casting material — the vacuum chamber, while the other simply hides it--the pressure chamber. The pressure chamber works by providing up to psi of atmospheric pressure.

If you remember your high school science, normal sea level pressure is about But, once you release the air pressure back to If your material was a mold rubber though, such as silicone or polyurethane, the flexible rubber will not contain the compressed air bubbles and they would expand within the rubber back to normal size, even though your rubber has cured.

Thus, the pressure pot is best used when your mold making or casting material cures to a solid and the vacuum chamber is used to remove air from flexible rubbers. The vacuum chamber can also de-air solid resins and epoxies, too. The last point to make is that to operate these two tools you will require a vacuum pump for the vacuum chamber and a compressor for the pressure pot.

Both items are not too expensive. A compressor used to operate a nail gun and available at big box stores is all you will need. In conclusion, if you are serious about mold making and casting as a hobby or as an income producing profession, then a vacuum chamber and pressure chamber are in your future. In summary, the vacuum chamber is used primarily to eliminate unsightly air bubbles in hard setting materials, whereas, the vacuum chamber can be used for both degassing rubber and hard setting materials, but is best adopted for rubbers such as silicones and polyurethanes.

In the mold of the present invention, the resilient interlocking pair comprise a male and a female member that are on opposing mold faces of the first mold portion and the second mold portion, respectively. The flat surface on the inside of the rim of an aircraft wheel on which the bead of the tire seats. When the housing is attached to a container, the at least one air channel allows air flow between the inside of a container and the housing. The housing of the device is inserted through this opening from the inside of the container. Density altitude. The housing collar 79 may comprise a variety of circumferential shapes, decorative or otherwise, including, for example, round, square, oval, triangular or any other polygonal shape.

Damaging silicone rubbers by evacuating air

Damaging silicone rubbers by evacuating air

Damaging silicone rubbers by evacuating air

Damaging silicone rubbers by evacuating air. Materials of Engineering

In operation, a resilient and self-locking mold of the present invention, which preferably has its first and second mold portions interlocked, is placed in one of the halves of a mold box, typically, an aluminum mold box , each mold box half being secured to an opposing platen. A resin dispensing line is connected to an orifice on the mold's surface, which is connected, via a channel to the mold cavity. A vacuum line is connected to the second orifice on the mold's surface, which is connected to the mold cavity.

The platen is activated and it moves toward the opposing platen, compressing the face of the first mold member against the opposing face of the second mold member. The compressed mold is thereby secured for the resin injection step. It is preferred that the platen be capable of delivering a predetermined amount of pressure to the mold portion.

Preferably, the platen is driven by air or hydraulic pressure. After the mold is secured between the platen and the lateral support, the void of the mold is evacuated of air, via the vacuum line, and a predetermined amount of liquid resin is forced into the evacuated mold. Once the void is filled with liquid resin, the vacuum line and fill lines are removed and the platen deactivated.

The unsecured mold is now capable of being placed to the side to allow the liquid resin therein to harden. The above process is then repeated using a second mold. In this embodiment, the void of each mold in the series is evacuated of air and filled with resin before proceeding to the next mold. Once the void of each mold in the series has been evacuated and filled, the platen is deactivated, the series of molds are removed from the device and the liquid resin in each is allowed to harden into the object to be molded without further need for external compression.

In yet another embodiment, a turntable may be used to feed empty molds to and remove filled molds from the resin filling site having the above described pressure driven platen. Thus, the above methods are characterized in that they eliminate the need for the vacuum box of the prior art. This is useful because it eliminates steps of opening and closing of the vacuum box, which are both fatiguing and time consuming. The above methods also increase throughput by eliminating the need to evacuate the entire vacuum box in order to evacuate the void in the mold.

Further, the above methods are characterized in that they also eliminate the need for the hand operated clamps for adjusting compression of the mold portions.

In either of the above embodiments, the compression provided by the platen is provided by hydraulic or air pressure. Preferably, the compression force is provided by air pressure.

The amount of compression that is to be applied in any instance must be sufficient to prevent any of the liquid resin that is injected into the void from squeezing out between the opposing faces of the mold portions.

By controlling the mold compression pressure, and by adding a vacuum chamber outside the void to receive any excess resin, the escape of resin between opposing mold faces is minimized. Typical compression pressures are from 50 to 60 pounds per square inch p. The vacuum pressures used in the above embodiments should not be so strong as to pull resin into the vacuum line during filling. Suitable vacuum pressure for use in the present invention varies depending upon the volume of the void, and the channel size through which the air travels from the void to the vacuum.

Those skilled in the art of vacuum assist prototype molding can readily determine the vacuum pressures to be used. Typically, suitable vacuum pressures range from 20 inches to 30 inches of mercury, preferably 26 to 30 inches. Typical channel sizes are from 0. Thus, in its third aspect, the present invention is also directed to an improved method for the prototype molding of a resin-based object.

Consistent with the above disclosure, FIGS. In particular, FIG. The recess 26 is shown as surrounding the cavity void 23 that is in the shape of the object to be molded.

The mold half 21 has an injection port 27 that is of sufficient size to receive a nozzle capable of injecting a moldable resin therein. When the mold halves 21 and 22 are compressed together, such that the ring 25 and the corresponding recess 26 interlock, the injection port 27 is connected to vent hole 29, via a series of open spaces 24, 23, 13 and 14, a hole 19 and a channel Space 24, which is connected to hole 27 disperses injected resin across the width of the mold cavity 23, which mold cavity with the core not shown in mold half 21 defines the shape of the object to be molded.

Overflow slot 13 is a narrow slot that is capable of receiving excess resin from the mold cavity 23 and directing its flow to overflow chamber Overflow chamber 14 has a hole 19, which is connected via channel 28, to a vent hole 29 on the exterior of the mold half The vent hole 29 is of suitable size for connecting to a vacuum line not shown.

Because vent hole 29 is ultimately connected to injection port 27, when the injection port is connected to a resin dispensing line and when a vacuum is applied across vent hole 29, the air in the space defined by elements 28, 14, 13, 23, and 24 is evacuated.

In FIG. Additional features shown in FIG. The mold box 40 has two mold halves 41 and 42, which when compressed together define a space therebetween that is suited for holding and compressing the mold halves 21 and 22 of FIG. Mold box half 41 has a hole 47 in its side face that is capable of providing access to injection port 27 when mold half 21 of FIG. Mold box half 42 has a nozzle 49 on its top face that is capable of providing access to vent hole 29, when mold half 22 of FIG.

Mold box halves 41 and 42 have plates 45 and 46, respectively which are affixed or integrally attached to the back of each mold half. These plates allow the mold halves 41 and 42 to be clamped or affixed to opposing platens.

To provide for a quick and proper alignment when mold box halves 41 and 42 are compressed together, mold box halves 41 and 42 each have wings 44c and 44b, respectively projecting from their respective side faces. These wings are in pairs on both side faces and are associated with male 44d and female 44b positioning members. Cavity 53 in mold box half 41 and cavity 58 in mold box half 42 are capable of receiving mold halves 21 and 22 of FIG. This device 60 employs the mold box halves 41 and 42 of FIGS.

Platen 56 is driven by a piston 62, which piston preferably is controlled by air pressure. Opposing platen 55 is fixed to table In practice, the mold halves of the present invention e. The mold halves may be interlocked to one another prior to placement in the mold box halves. Alternatively, the mold halves 21 and 22 may be placed in their respective mold box halves 41 and 42, which are then compressed together by piston 62, causing the mold halves to interlock.

In practice, the interlocked mold halves are compressed together at a predetermined pressure, typically psi.

A vacuum line 59 is attached to a vacuum nozzle 49 for evacuating air from the mold cavity not shown. A nozzle not shown , such as from a static mixer, is used for injecting a liquid resin into hole After the vacuum has evacuated air from the mold cavity not shown , an amount of liquid resin sufficient to fill the mold cavity is injected via hole After injection, the injection line not shown and vacuum line 59 are removed from the mold.

The piston 62 is then drawn back to the left separating mold box halves 41 and 42 and exposing the resilient and self-locking mold of the present invention which is filled with liquid resin. The exposed and interlocked mold containing the liquid resin then is completely withdrawn from the remaining mold half and placed to the side until the liquid resin sets.

While the resin is setting, a second resilient and self locking mold of the present invention is capable of being inserted into the mold box and the process repeated. A two piece resilient and self-locking mold of the present invention was made to duplicate a model of a beeper-sized housing half shell.

To make the female half of the two piece mold, the model half shell was mounted to a board and partings were added to eliminate as many undercuts as possible.

Gating i. A circular tube corresponding to a male member of the interlocking pair was added, circumscribing the object to be molded.

Shapes corresponding to the vacuum chamber and the overflow chamber were then added. Thereafter, a conventional mold release agent was sprayed over the entire parting and an aluminum mold box half. The sprayed mold box half was placed over the mounted, parted and sprayed model and a two part silicone molding composition, i. The silicone was allowed to cure for eight hours.

After the silicone cured, the aluminum box containing the silicone was separated from the parting. The model, the gating, and the male member of the interlocking pair remain behind. Thereafter, all partings and the male member of the interlocking pair were removed. The female portion of the mold was examined and cleaned where necessary.

A vacuum vent, with a channel connecting to the overflow chamber was added. Gating was then added and the cores corresponding to the shapes of the vacuum chamber and the overflow were allowed to remain. A mold release agent was sprayed into a second mold box and over the entire face of the first mold half with partings, gating and chambers.

A second aluminum mold box was placed over the partings and the female portion of the mold. A silicone resin was then poured into the second mold half through a hole therein.

The resin was allowed to cure for eight hours. After curing, the aluminum mold box halves were pulled apart, and all gating, parting chambers and the model were removed. The resulting embodiment of a two piece and self locking mold of the present invention was now ready for use. A mold release agent was sprayed on the opposing mold faces of the two mold halves that were made in Example 1. The mold halves were placed in an aluminum mold box i.

A vacuum line was connected to the vacuum vent. A static mixer for dispensing a molding resin was connected to the injection port. The vacuum line was turned off and resin dispensing lines were then removed. The two piece self-locking mold, while still interlocked was removed from the aluminum mold box and set aside about fifteen minutes for curing.

After the part was cured, the silicone mold halves were pulled apart and this newly molded part stuck to the female half of the mold.

Pressure from an air hose was used to blow the new part out of the female half of the mold. The gates and vents were cleaned from the part producing a perfect duplicate of the original model of a beeper sized housing half-shell. All rights reserved. A SumoBrain Solutions Company. Login Sign up. Search Expert Search Quick Search. Device for prototype molding.

United States Patent In addition, the present invention is directed to a method for the rapid prototype molding of a resinous object using the above described resilient and self-locking mold. Megleo, Bruce A. Benton, Palatine, IL, Click for automatic bibliography generation. What is claimed is: 1. The mold of claim 1 wherein said opposing members of said resilient interlocking pair are a resilient ring and a corresponding resilient recess, said resilient recess being of sufficient size and shape to releasably interlock with said resilient ring.

The mold of claim 2 wherein said first mold portion and said second mold portion are composed of a resilient silicone rubber. The mold of claim 3 wherein said ring is an integral part of said first mold portion or said second mold portion.

The mold of claim 5 further containing a vacuum chamber in communication with said second channel and said void and capable of receiving excess liquid resin introduced into said void. In the improved mold of claim 7, said resilient interlocking pair comprising a ring or a recess surrounding said cavity on said first opposing face and a recess or a ring, respectively, surrounding said core on said second opposing face, said recess being of sufficient size, shape and position to snugly and reversibly interlock with said ring.

In the improved mold of claim 8, said ring being made of the same material as the opposing face to which it is attached. In the improved mold of claim 10, said ring being attached along its length to said mold face by a neck. In the improved mold of claim 11, said ring being integrally attached along its length to said mold face by said neck. Field of the Invention The present invention relates to an improved mold, device and method for the prototype molding of an object in resin under reduced pressure.

In particular, the method of the present invention comprises the steps of: a. Cast molding of intraocular lenses. Vacuum cast molding apparatus. Chocolate shape mold assembly. Method of making an epoxy mold. Process and apparatus for the production of spectacle frame parts of synthetic material. Molding apparatus for a composite billiard ball. It also acts as a biocidal agent and prevents the formation of microbial contamination in the tanks.

Antidrag wire. A structural wire inside a Pratt truss airplane wing between the spars. Antidrag wires run from the rear spar inboard, to the front spar at the next bay outboard.

Antidrag wires oppose the forces that try to pull the wing forward. Antiservo tab. A tab installed on the trailing edge of a stabilator to make it less sensitive. The tab automatically moves in the same direction as the stabilator to produce an aerodynamic force that tries to bring the surface back to a streamline position.

This tab is also called an antibalance tab. Antiskid brake system. If any wheel decelerates too rapidly, indicating an impending skid, pressure to that bake is released and the wheel stops decelerating. Pressure is then reapplied at a slightly lower value. Antitear strip. Strips of aircraft fabric laid under the reinforcing tape before the fabric is stitched to an aircraft wing. Arbor press. A press with either a mechanically or hydraulically operated ram used in a maintenance shop for a variety of pressing functions.

Aspect ratio. The ratio of the length, or span, of an airplane wing to its width, or chord. For a nonrectangular wing, the aspect ratio is found by dividing the square of the span of the wing by its area.

Asymmetrical airfoil. An airfoil section that is not the same on both sides of the chord line. Asymmetrical lift. A condition of uneven lift produced by the rotor when a helicopter is in forward flight. Asymmetrical lift is caused by the difference between the airspeed of the advancing blade and that of the retreating blade. Attitude indicator. A gyroscopic flight instrument that gives the pilot an indication of the attitude of the aircraft relative to its pitch and roll axes.

The attitude indicator in an autopilot is in the sensing system that detects deviation from a level flight attitude. Augmenter tube. A long, stainless steel tube around the discharge of the exhaust pipes of a reciprocating engine.

Exhaust gases flow through the augmenter tube and produce a low pressure that pulls additional cooling air through the engine compartment. Heat may be taken from the augmenter tubes and directed through the leading edges of the wings for thermal anti-icing. A pressure vessel inside of which air can be heated to a high temperature and pressure raised to a high value.

Autoclaves are used in the composite manufacturing industry to apply heat and pressure for curing resins. A heavier-than-air rotor-wing aircraft sustained in the air by rotors turned by aerodynamic forces rather than by engine power. When the name Autogiro is spelled with a capital A, it refers to a specific series of machines built by Juan de la Cierva or his successors. Autoignition system.

A system on a turbine engine that automatically energizes the igniters to provide a relight if the engine should flame out. Automatic adjuster. A subsystem in an aircraft disk brake that compensates for disk or lining wear.

Each time the brakes are applied, the automatic adjuster is reset for zero clearance, and when the brakes are released, the clearance between the disks or the disk and lining is returned to a preset value.

A malfunctioning automatic adjuster in a multiple-disk brake can cause sluggish and jerky operation. Automatic flight control system AFCS. The full system of automatic flight control that includes the autopilot, flight director, horizontal situation indicator, air data sensors, and other avionics inputs. Automatic pilot autopilot. The primary purpose of an autopilot is to relieve the pilot of the control of the aircraft during long periods of flight. Descent of a helicopter without the use of engine power.

An aerodynamic force causes the rotors to rotate. Autosyn system. A synchro system used in remote indicating instruments.

The rotors in an Autosyn system are two-pole electromagnets, and the stators are delta-connected, three-phase, distributed-pole windings in the stator housings. The rotors in the transmitters and indicators are connected in parallel and are excited with volt, Hz AC. The rotor in the indicator follows the movement of the rotor in the transmitter. Auxiliary power unit APU. A small turbine or reciprocating engine that drives a generator, hydraulic pump, and air pump. The APU is installed in the aircraft and is used to supply electrical power, compressed air, and hydraulic pressure when the main engines are not running.

Aviation snips. Compound-action hand shears used for cutting sheet metal. Aviation snips come in sets of three. One pair cuts to the left, one pair cuts to the right, and the third pair of snips cuts straight. The branch of technology that deals with the design, production, installation, use, and servicing of electronic equipment mounted in aircraft.

A horizontal angular distance, measured clockwise from a fixed reference direction to an object. Back course. When flying a back-course approach, the aircraft approaches the instrument runway from the end on which the localizer antennas are installed. Backhand welding. Welding in which the torch is pointed away from the direction the weld is progressing. Backplate brake component.

A floating plate on which the wheel cylinder and the brake shoes attach on an energizingtype brake. Backup ring. A flat leather or Teflon ring installed in the groove in which an O-ring or T-seal is placed. The backup ring is on the side of the seal away from the pressure, and it prevents the pressure extruding the seal between the piston and the cylinder wall.

Balance cable. A cable in the aileron system of an airplane that connects to one side of each aileron. When the control wheel is rotated, a cable from the cockpit pulls one aileron down and relaxes the cable going to the other aileron. The balance cable pulls the other aileron up. Balance panel. A flat panel hinged to the leading edge of some ailerons that produces a force which assists the pilot in holding the ailerons deflected.

The balance panel divides a chamber ahead of the aileron in such a way that when the aileron is deflected downward, for example, air flowing over its top surface produces a low pressure that acts on the balance panel and causes it to apply an upward force to the aileron leading edge.

Balance tab. An adjustable tab mounted on the trailing edge of a control surface to produce a force that aids the pilot in moving the surface. The tab is automatically actuated in such a way it moves in the direction opposite to the direction the control surface on which it is mounted moves. Balanced actuator. A linear hydraulic or pneumatic actuator that has the same area on each side of the piston.

Banana oil. Nitrocellulose dissolved in amyl acetate, so named because it smells like bananas. Barometric scale. A small window in the dial of a sensitive altimeter in which the pilot sets the barometric pressure level from which the altitude shown on the altimeter is measured. The electrode of a bipolar transistor between the emitter and the collector.

Varying a small flow of electrons moving into or out of the base controls a much larger flow of electron between the emitter and the collector. Varying a small flow of electrons moving into or out of the base controls a much larger flow of electrons between the emitter and the collector. Bead tire component. The high-strength carbon-steel wire bundles that give an aircraft tire its strength and stiffness where it mounts on the wheel.

Bead seat area. The flat surface on the inside of the rim of an aircraft wheel on which the bead of the tire seats. Bearing strength sheet metal characteristic. The amount of pull needed to cause a piece of sheet metal to tear at the points at which it is held together with rivets.

The bearing strength of a material is affected by both its thickness and the diameter of the rivet. Beehive spring. A hardened-steel, coil-spring retainer used to hold a rivet set in a pneumatic rivet gun. This spring gets its name from its shape. It screws onto the end of the rivet gun and allows the set to move back and forth, but prevents it being driven from the gun.

Bend allowance. The amount of material actually used to make a bend in a piece of sheet metal. Bend allowance depends upon the thickness of the metal and the radius of the bend, and is normally found in a bend allowance chart. Bend tangent line. A line made in a sheet metal layout that indicates the point at which the bend starts.

The basic principle that explains the relation between kinetic energy and potential energy in fluids that are in motion. The rim that holds the glass cover in the case of an aircraft instrument.

Bias-cut surface tape. Bias-cut tape may be stretched around a compound curve such as a wing tip bow without wrinkling. Bilge area. A low portion in an aircraft structure in which water and contaminants collect. The area under the cabin floorboards is normally called the bilge.

Bipolar transistor. A solid-state component in which the flow of current between its emitter and collector is controlled by a much smaller flow of current into or out of its base. Blade track. The condition of a helicopter rotor in which each blade follows the exact same path as the blade ahead of it.

Black box. A term used for any portion of an electrical or electronic system that can be removed as a unit. A black box does not have to be a physical box. Bladder-type fuel cell. A plastic-impregnated fabric bag supported in a portion of an aircraft structure so that it forms a cell in which fuel is carried. A material such as glass cloth or mat that is placed over a composite lay-up to absorb the excess resin forced out of the ply fibers when pressure is applied.

Bleeding dope. Dope whose pigments are soluble in the solvents or thinners used in the finishing system. The color will bleed up through the finished coats. Bleeding of brakes. The maintenance procedure of removing air entrapped in hydraulic fluid in the brakes. Fluid is bled from the brake system until fluid with no bubbles flows out.

A defect in a lacquer or dope finish caused by moisture condensing on the surface before the finish dries. If the humidity of the air is high, the evaporation of the solvents cools the air enough to cause the moisture to condense. The water condensed from the air mixes with the lacquer or dope and forms a dull, porous, chalky-looking finish called blush.

A blushed finish is neither attractive nor protective. The process of electrically connecting all isolated components to the aircraft structure. Bonding provides a path for return current from electrical components, and a low-impedance path to ground to minimize static electrical charges.

Shock-mounted components have bonding braids connected across the shock mounts. Boost pump. An electrically driven centrifugal pump mounted in the bottom of the fuel tanks in large aircraft. Boost pumps provide a positive flow of fuel under pressure to the engine for starting and serve as an emergency backup in the event an engine-driven pump should fail. They are also used to transfer fuel from one tank to another and to pump fuel overboard when it is being dumped.

Boost pumps prevent vapor locks by holding pressure on the fuel in the line to the engine-driven pump. Centrifugal boost pumps have a small agitator propeller on top of the impeller to force vapors from the fuel before it leaves the tank. Boundary layer. The layer of air that flows next to an aerodynamic surface. Because of the design of the surface and local surface roughness, the boundary layer often has a random flow pattern, sometimes even flowing in a direction opposite to the direction of flight.

A turbulent boundary layer causes a great deal of aerodynamic drag. Bourdon tube. It consists of a sealed, curved tube with an elliptical cross section. Pressure inside the tube tries to straighten it, and as it straightens, it moves a pointer across a calibrated dial. Bourdon-tube pressure gauges are used to measure temperature by measuring the vapor pressure in a sealed container of a volatile liquid, such as methyl chloride, whose vapor pressure varies directly with its temperature.

A method of thermally joining metal parts by wetting the surface with a molten nonferrous alloy. When the molten material cools and solidifies, it holds the pieces together. British thermal unit BTU. Bucking bar. A heavy steel bar with smooth, hardened surfaces, or faces. The bucking bar is held against the end of the rivet shank when it is driven with a pneumatic rivet gun, and the shop head is formed against the bucking bar.

Bulb angle. An L-shaped metal extrusion having an enlarged, rounded edge that resembles a bulb on one of its legs. A structural partition that divides the fuselage of an aircraft into compartments, or bays. Bungee shock cord. A cushioning material used with the nonshock absorbing landing gears installed on older aircraft.

Bungee cord is made up of many small rubber bands encased in a loose-woven cotton braid. Burnish verb. To smooth the surface of metal that has been damaged by a deep scratch or gouge.

The metal piled up at the edge of the damage is pushed back into the damage with a smooth, hard steel burnishing tool. A sharp rough edge of a piece of metal left when the metal was sheared, punched, or drilled. A point within an electrical system from which the individual circuits get their power. Buttock line. A line used to locate a position to the right or left of the center line of an aircraft structure.

Trade name for a synthetic rubber product made by the polymerization of isobutylene. Butyl withstands such potent chemicals as phosphate ester-base Skydrol hydraulic fluids. Cage verb. To lock the gimbals of a gyroscopic instrument so it will not be damaged by abrupt flight maneuvers or rough handling. Calendar month. A measurement of time used by the FAA for inspection and certification purposes.

One calendar month from a given day extends from that day until midnight of the last day of that month. Calender fabric treatment. To pass fabric through a series of heated rollers to give it a smooth shiny surface.

Calibrated airspeed CAS. Indicated airspeed corrected for position error. See position error. Canted rate gyro. A rate gyro whose gimbal axis is tilted so it can sense rotation of the aircraft about its roll axis as well as its yaw axis. Camber wheel alignment. The amount the wheels of an aircraft are tilted, or inclined, from the vertical.

If the top of the wheel tilts outward, the camber is positive. If the top of the wheel tilts inward, the camber is negative. A horizontal control surface mounted ahead of the wing to provide longitudinal stability and control.

Cantilever wing. A wing that is supported by its internal structure and requires no external supports. The wing spars are built in such a way that they carry all the bending and torsional loads. Cap strip. The main top and bottom members of a wing rib.

The cap strips give the rib its aerodynamic shape. Capacitance-type fuel quantity measuring system. A popular type of electronic fuel quantity indicating system that has no moving parts in the fuel tank. The tank units are cylindrical capacitors, called probes, mounted across the tank, from top to bottom.

The dielectric between the plates of the probes is either fuel or the air above the fuel, and the capacitance of the probe varies with the amount of fuel in the tank. The indicator is a servo-type instrument driven by the amplified output of a capacitance bridge. Capillary tube. A soft copper tube with a small inside diameter.

The capillary tube used with vapor-pressure thermometer connects the temperature sensing bulb to the Bourdon tube.

The capillary tube is protected from physical damage by enclosing it in a braided metal wire jacket. Carbon monoxide detector. A packet of chemical crystals mounted in the aircraft cockpit or cabin where they are easily visible. The crystals change their color from yellow to green when they are exposed to carbon monoxide. Field current is controlled by varying the resistance of a stack of thin carbon disks. This resistance is varied by controlling the amount the stack is compressed by a spring whose force is opposed by the pull of an electromagnet.

Carburizing flame. An oxyacetylene flame produced by an excess of acetylene. This flame is identified by a feather around the inner cone.

A carburizing flame is also called a reducing flame. Carcass tire component. The layers of rubberized fabric that make up the body of an aircraft tire. Case pressure. A low pressure that is maintained inside the case of a hydraulic pump.

If a seal becomes damaged, hydraulic fluid will be forced out of the pump rather than allowing air to be drawn into the pump.

Cathode-ray tube CRT. A display tube used for oscilloscopes and computer video displays. An electron gun emits a stream of electrons that is attracted to a positively charged inner surface of the face of the tube.

Acceleration and focusing grids speed the movement of the electrons and shape the beam into a pinpoint size. Electrostatic or electromagnetic forces caused by deflection plates or coils move the beam over the face of the tube. The inside surface of the face of the tube is treated with a phosphor material that emits light when the beam of electrons strikes it. A condition that exist in a hydraulic pump when there is not enough pressure in the reservoir to force fluid to the inlet of the pump.

The pump picks up air instead of fluid. Center of gravity. The location on an aircraft about which the force of gravity is concentrated. Center of lift. The location of the chord line of an airfoil at which all the lift forces produced by the airfoil are considered to be concentrated. Center of pressure. The point on the chord line of an airfoil where all of the aerodynamic forces are considered to be concentrated.

Centering cam. A cam in the nose-gear shock strut that causes the piston to center when the strut fully extends. When the aircraft takes off and the strut extends, the wheel is straightened in its fore-and-aft position so it can be retracted into the wheel well.

Charging stand air conditioning service equipment. A handy and compact arrangement of air conditioning servicing equipment. A charging stand contains a vacuum pump, a manifold gauge set, and a method of measuring and dispensing the refrigerant.

A type of rapid vibration of a hydraulic pump caused by the pump taking in some air along with the hydraulic fluid. Check wood defect. Check valve. A hydraulic or pneumatic system component that allows full flow of fluid in one direction but blocks all flow in the opposite direction. Chemical oxygen candle system. An oxygen system used for emergency or backup use. Solid blocks of material that release oxygen when they are burned are carried in special fireproof fixtures.

When oxygen is needed, the candles are ignited with an integral igniter, and oxygen flows into the tubing leading to the masks. Chevron seal. A form of one-way seal used in some fluidpower actuators. A chevron seal is made of a resilient material whose cross section is in the shape of the letter V. The pressure being sealed must be applied to the open side of the V. An alloy of nickel and chromium used as the positive element in a thermocouple for measuring exhaust gas temperature.

A closed plane figure with every point an equal distance from the center. A circle has the greatest area for its circumference of any enclosed shape. Circuit breaker. An electrical component that automatically opens a circuit any time excessive current flows through it.

A circuit breaker may be reset to restore the circuit after the fault causing the excessive current has been corrected. Clad aluminum. A sheet of aluminum alloy that has a coating of pure aluminum rolled on one or both of its surfaces for corrosion protection.

Clamp-on ammeter. An electrical instrument used to measure current without opening the circuit through which it is flowing. The jaws of the ammeter are opened, slipped over the current carrying wire, and then clamped shut. Cleco fastener.

A patented spring-type fastener used to hold metal sheets in position until they can be permanently riveted together. Close-quarter iron. This iron is used for heatshrinking polyester fabrics in areas that would be difficult to work with a large iron. Closed assembly time. The time elapsing between the assembly of glued joints and the application of pressure. Closed-center hydraulic system.

A hydraulic system in which the selector valves are installed in parallel with each other. When no unit is actuated, fluid circulates from the pump back to the reservoir without flowing through any of the selector valves. Closed-center selector valve. A type of flow-control valve used to direct pressurized fluid into one side of an actuator, and at the same time, direct the return fluid from the other side of the actuator to the fluid reservoir.

Closed-center selector valves are connected in parallel between the pressure manifold and the return manifold. Rotating about the same axis. Coaxial rotors of a helicopter are mounted on concentric shafts in such a way that they turn in opposite directions to cancel torque.

Coaxial cable. A special type of electrical cable that consists of a central conductor held rigidly in the center of a braided outer conductor. Coaxial cable, commonly called coax, is used for attaching radio receivers and transmitters to their antenna. Coefficient of drag. A dimensionless number used in the formula for determining induced drag as it relates to the angle of attack. Coefficient of lift. A dimensionless number relating to the angle of attack used in the formula for determining aerodynamic lift.

Coin dimpling. A process of preparing a hole in sheet metal for flush riveting. A coining die is pressed into the rivet hole to form a sharp-edged depression into which the rivet head fits. Collective pitch control. The helicopter control that changes the pitch of all of the rotor blades at the same time. Movement of the collective pitch control increases or decreases the lift produced by the entire rotor disk. Combustion heater. A type of cabin heater used in some aircraft. Gasoline from the aircraft fuel tanks is burned in the heater.

Compass fluid. A highly refined, water-clear petroleum product similar to kerosene. Compass fluid is used to dampen the oscillations of magnetic compasses. Compass rose. Compass swinging. A maintenance procedure that minimizes deviation error in a magnetic compass.

The aircraft is aligned on a compass rose, and the compensating magnets in the compass case are adjusted so the compass card indicates the direction marked on the rose.

After the deviation error is minimized on all headings, a compass correction card is completed and mounted on the instrument panel next to the compass. Compensated fuel pump. A vane-type, engine-driven fuel pump that has a diaphragm connected to the pressure regulating valve. The chamber above the diaphragm is vented to the carburetor upper deck where it senses the pressure of the air as it enters the engine.

The diaphragm allows the fuel pump to compensate for altitude changes and keeps the carburetor inlet fuel pressure a constant amount higher than the carburetor inlet air pressure. Compensator port brake system component. A small hole between a hydraulic brake master cylinder and the reservoir. When the brakes are released, this port is uncovered and the fluid in the master cylinder is vented to the reservoir.

When the brake is applied, the master-cylinder piston covers the compensator port and allows pressure in the line to the brake to build up and apply the brakes.

When the brake is released, the piston uncovers the compensator port. If any fluid has been lost from the brake, the reservoir will refill the master cylinder. A restricted compensator port will cause the brakes to drag or will cause them to be slow to release.

Something made up of different materials combined in such a way that the characteristics of the resulting material are different from those of any of the components.

Compound curve. The surface of a sphere is a compound curve. Compound gauge air conditioning servicing equipment. A pressure gauge used to measure the pressure in the low side of an air conditioning system. A compound gauge is calibrated from zero to 30 inches of mercury vacuum, and from zero to about psi positive gauge pressure. Compressibility effect. The sudden increase in the total drag of an airfoil in transonic flight caused by formation of shock waves on the surface.

Compression failure. A type of structural failure in wood caused by the application of too great a compressive load. A compression failure shows up as a faint line running at right angles to the grain of the wood. Compression strut. A heavy structural member, often in the form of a steel tube, used to hold the spars of a Pratt truss airplane wing apart.

A compression strut opposes the compressive loads between the spars arising from the tensile loads produced by the drag and antidrug wires. Compression wood. A defect in wood that causes it to have a high specific gravity and the appearance of an excessive growth of summerwood. Any material containing compression wood is unsuited for aircraft structural use and must be rejected. Compressor air conditioning system component. The component in a vapor-cycle cooling system in which the low-pressure refrigerant vapors, after they leave the evaporator, are compressed to increase both their temperature and pressure before they pass into the condenser.

Concave surface. A surface that is curved inward. The outer edges are higher than the center. Condenser air conditioning system component. The component in a vapor-cycle cooling system in which the heat taken from the aircraft cabin is given up to the ambient air outside the aircraft.

Conductor electrical. A material that allows electrons to move freely from one atom to another within the material. Coning angle. The angle formed between the plane of rotation of a helicopter rotor blade when it is producing lift and a line perpendicular to the rotor shaft. The degree of the coning angle is determined by the relationship between the centrifugal force acting on the blades and the aerodynamic lift produced by the blades. Constant mathematical. A value used in a mathematical computation that is the same every time it is used.

For example, the relationship between the length of the circumference of a circle and the length of its diameter is a constant, 3. Constant differential mode cabin pressurization. The mode of pressurization in which the cabin pressure is maintained a constant amount higher than the outside air pressure.

The maximum differential pressure is determined by the structural strength of the aircraft cabin. Constant-displacement pump. Some form of pressure regulator or relief valve must be used with a constant displacement pump when it is driven by an aircraft engine.

Constant-speed drive CSD. A special drive system used to connect an alternating current generator to an aircraft engine. The drive holds the generator speed and thus its frequency constant as the engine speed varies.

A copper-nickel alloy used as the negative lead of a thermocouple for measuring the cylinder head temperature of a reciprocating engine. A remotely actuated, heavy-duty electrical switch. Continuity tester. A troubleshooting tool that consists of a battery, a light bulb, and test leads.

The test leads are connected to each end of the conductor under test, and if the bulb lights up, there is continuity. If it does not light up, the conductor is open. Continuous Airworthiness Inspection Program. An inspection program that is part of a continuous airworthiness maintenance program approved for certain large airplanes to which 14 CFR Part is not applicable , turbojet multi-engine airplanes, turbopropeller-powered multi-engine airplanes, and turbine-powered rotorcraft.

Continuous-duty solenoid. A solenoid-type switch designed to be kept energized by current flowing through its coil for an indefinite period of time. Current flows through its coil all the time the battery is connected to the electrical system.

Continuous-flow oxygen system. A type of oxygen system that allows a metered amount of oxygen to continuously flow into the mask. A rebreather-type mask is used with a continuous-flow system. Continuous-loop fire-detection system. A fire-detection system that uses a continuous loop of two conductors separated with a thermistor-type insulation.

Under normal temperature conditions, the thermistor material is an insulator; but if it is exposed to a fire, the thermistor changes into a conductor and completes the circuit between the two conductors, initiating a fire warning. Control horn. The arm on a control surface to which the control cable or push-pull rod attaches to move the surface.

Control stick. The type of control device used in some airplanes. A vertical stick in the flight deck controls the ailerons by side-to-side movement and the elevators by foreand- aft movement. Control yoke. The movable column on which an airplane control wheel is mounted.

The yoke may be moved in or out to actuate the elevators, and the control wheel may be rotated to actuate the ailerons.

Conventional current. An imaginary flow of electricity that is said to flow from the positive terminal of a power source, through the external circuit to its negative terminal. The arrowheads in semiconductor symbols point in the direction of conventional current flow. Converging duct. A duct, or passage, whose cross-sectional area decreases in the direction of fluid flow. Conversion coating. A chemical solution used to form an airtight oxide or phosphate film on the surface of aluminum or magnesium parts.

The conversion coating prevents air from reaching the metal and keeps it from corroding. Convex surface. A surface that is curved outward. The outer edges are lower than the center. Coriolis effect. The change in rotor blade velocity to compensate for a change in the distance between the center of mass of the rotor blade and the axis rotation of the blade as the blades flap in flight.

Cornice brake. A large shop tool used to make straight bends across a sheet of metal. Cornice brakes are often called leaf brakes. Corrugated metal. Cotter pin. A split metal pin used to safety a castellated or slotted nut on a bolt. The pin is passed through the hole in the shank of the bolt and the slots in the nut, and the ends of the pin are spread to prevent it backing out of the hole. Preparation of a rivet hole for a flush rivet by beveling the edges of the holes with a cutter of the correct angle.

Coverite surface thermometer. A small surface-type bimetallic thermometer that calibrates the temperature of an iron used to heat-shrink polyester fabrics. Pointing the nose of an aircraft into the wind to compensate for wind drift. A form of stress-caused damage that occurs in a transparent thermoplastic material. Crazing appears as a series of tiny, hair-like cracks just below the surface of the plastic. Critical Mach number. The flight Mach number at which there is the first indication of supersonic airflow over any part of the aircraft structure.

Cross coat. A double coat of aircraft finishing material in which the second coat is sprayed at right angles to the first coat, before the solvents have evaporated from the first coat. Cross-feed valve fuel system component. A valve in a fuel system that allows any of the engines of a multi-engine aircraft to draw fuel from any fuel tank. Cross-feed systems are used to allow a multi-engine aircraft to maintain a balanced fuel condition. Cross-flow valve.

An automatic flow-control valve installed between the gear-up and gear-down lines of the landing gear of some large airplanes. When the landing gear is released from its uplocks, its weight causes it to fall faster than the hydraulic system can supply fluid to the gear-down side of the actuation cylinder.

The cross-flow valve opens and directs fluid from the gear-up side into the gear-down side. This allows the gear to move down with a smooth motion. Cryogenic liquid. Cuno filter. The registered trade name for a particular style of edge-type fluid filter.

Cuno filters are made up of a stack of thin metal disks that are separated by thin scraper blades. Contaminants collect on the edge of the disks, and they are periodically scraped out and allowed to collect in the bottom of the filter case for future removal. Current limiter. An electrical component used to limit the amount of current a generator can produce.

Some current limiters are a type of slow-blow fuse in the generator output. Cyclic pitch control. The helicopter control that allows the pilot to change the pitch of the rotor blades individually, at a specific point in their rotation. The cyclic pitch control allows the pilot to tilt the plane of rotation of the rotor disk to change the direction of lift produced by the rotor.

Data bus. A wire or group of wires that are used to move data within a computer system. Debooster valve. A valve in a power brake system between the power brake control valve and the wheel cylinder.

This valve lowers the pressure of the fluid going to the brake and increases its volume. A debooster valve increases the smoothness of brake application and aids in rapid release of the brakes. The breakdown of the structure of wood fibers. Wood that shows any indication of decay must be rejected for use in aircraft structure.

A type of tree that sheds its foliage at the end of the growing season. Hardwoods come from deciduous trees. Dedicated computer. A small digital computer, often built into an instrument or control device that contains a built-in program that causes it to perform a specific function.

Deep-vacuum pump. A deep vacuum pump can reduce the pressure inside the system to a few microns of pressure. Deflator cap. A cap for a tire, strut, or accumulator air valve that, when screwed onto the valve, depresses the valve stem and allows the air to escape safely through a hole in the side of the cap.

Delivery air duct check valve. An isolation valve at the discharge side of the air turbine that prevents the loss of pressurization through a disengaged cabin air compressor. Delta airplane. An airplane with a triangular-shaped wing. Delta connection electrical connection. A method of connecting three electrical coils into a ring or, as they are drawn on a schematic diagram as a triangle, a delta D. Density altitude. The altitude in standard air at which the density is the same as that of the existing air.

The ratio of the density of the air at a given altitude to the density of the air at sea level under standard conditions. Derated electrical specification. Derating is done to extend the life or reliability of the device. Desiccant air conditioning component.

A drying agent used in an air conditioning system to remove water from the refrigerant. A desiccant is made of silica-gel or some similar material. A spring-loaded pin or tab that enters a hole or groove when the device to which it is attached is in a certain position.

Detents are used on a fuel valve to provide a positive means of identifying the fully on and fully off position of the valve. An explosion, or uncontrolled burning of the fuel-air mixture inside the cylinder of a reciprocating engine.

Detonation occurs when the pressure and the temperature inside the cylinder become higher than the critical pressure and temperature of the fuel. Detonation is often confused with preignition. Deviation error. An error in a magnetic compass caused by localized magnetic fields in the aircraft. A compass must be compensated so the deviation error on any heading is no greater than 10 degrees.

Dewar bottle. A vessel designed to hold liquefied gases. It has double walls with the space between being evacuated to prevent the transfer of heat.

The surfaces in the vacuum area are made heat-reflective. Differential aileron travel. Aileron movement in which the upward-moving aileron deflects a greater distance than the one moving downward.

The up aileron produces parasite drag to counteract the induced drag caused by the down aileron. Differential aileron travel is used to counteract adverse yaw. Differential pressure.

The difference between two pressures. An airspeed indicator is a differential-pressure gauge. It measures the difference between static air pressure and pitot air pressure. A type of reverse-current cutout switch used with heavy-duty electrical systems.

Digital multimeter. The indication is in the form of a liquid crystal display in discrete numbers. The positive angle formed between the lateral axis of an airplane and a line that passes through the center of the wing or horizontal stabilizer. Dihedral increases the lateral stability of an airplane. Diluter-demand oxygen system. A popular type of oxygen system in which the oxygen is metered to the mask, where it is diluted with cabin air by an airflow-metering aneroid assembly which regulates the amount of air allowed to dilute the oxygen on the basis of cabin altitude.

The mixture of oxygen and air flows only when the wearer of the mask inhales. A diluter-demand regulator has an emergency position which allows percent oxygen to flow to the mask, by-passing the regulating mechanism. Dipole antenna. A half wavelength, center-fed radio antenna. The length of each of the two arms is approximately one fourth of the wavelength of the center frequency for which the antenna is designed. A large, cigar-shaped, rigid, lighter-than-air flying machine.

Dirigibles are made of a rigid truss structure covered with fabric. Gas bags inside the structure contain the lifting gas, which is either helium or hydrogen. Disc area helicopter specification. The total area swept by the blades of a helicopter main rotor. Diverging duct. A duct, or passage, whose cross-sectional area increases in the direction of fluid flow.

Dope proofing. The treatment of a structure to be covered with fabric to keep the solvents in the dope from softening the protective coating on the structure. Dope roping.

A condition of aircraft dope brushed onto a surface in such a way that it forms a stringy, uneven surface rather than flowing out smoothly.

Double-acting actuator hydraulic system component. A linear actuator moved in both directions by fluid power. Double-acting hand pump hydraulic system component. A hand-operated fluid pump that moves fluid during both strokes of the pump handle. A piece of sheet metal used to strengthen and stiffen a repair in a sheet metal structure.

Vacuum Degassing Chambers and Vacuum Pumps. Gallery FAQ's. If not removed before the material cures the air bubbles can cause defects such as nodules, cavities and hollows in the finishes cast. With electrical and electronic encapsulation then these air bubbles can cause electrical breakdown.

On intricate castings additional work will be required to correct the defects caused by the air bubbles. All Epoxy Resins, Araldites, Silicone Rubbers as well as any other mixed materials to be degassed will expand during the degassing process. It is essential that a container of sufficient volume is used. It is not uncommon for materials to expand two to six times their initial volume while degassing.

As the bubbles burst at the surface the expansion decreases. This process can take several minutes depending on the viscosity of the material, the speed of the vacuum pump and the volume of the vacuum chamber. Do take heed of both the viscosity and the pot life of the materials to be degassed. Materials with a very high viscosity will take a lot longer. Some very high viscosity materials will be very difficult to degas. If the pot life is short then speed could be essential.

That is essentially the pot life. Put a small sample in a container in the vacuum chamber and while closely observing through the lid see when the surface of the material starts to bubble. Use the vacuum isolation valve to stop pumping as soon as the first bubbles appear.

Make a note of the pressure shown on the pressure gauge. Some materials will start to degas at quite high pressures — in excess of 50 Mbar. Some materials will also seem to outgas for a very long time. This could be due to the pressure being too low and some of the volatiles in the material being evaporated off. The vacuum should only be held for a short period once bubbles are seen at the surface of the mixture, otherwise the chemical structure will be altered and curing time, so care should be taken with such materials to degas at a pressure which removes the air but does not start to evaporate the material or constituent parts of that material.

Once you are satisfied and confident the materials you are using are not gong to cause problems then proceed. Remove the vacuum chamber lid. Ensure that both the vent and vacuum isolation valves are closed and switch on the vacuum pump to warm up.

Measure out the required amount of material together with any hardeners or fillers into a clean bucket of adequate size to allow for expansion. Mix well, either by hand or with an electric mixer. Place the bucket in the vacuum chamber and replace the lid.

Gently open the vacuum isolation valve. Some light hand pressure on the lid may be required to establish a good seal — you will see on the gauge when the pressure starts to fall indicating a seal has been made.

Observe the surface of the material. Once bubbles start to come to the surface and break close the vacuum isolation valve. If the bubbles subside after a short time open the valve again. Repeat that process so that you progressively pump the chamber down. If there is a rapid rise in the level of the degassing material close the vacuum isolation valve and allow a little air back into the chamber with the vent valve. Continue pumping down and by balancing both the vacuum isolation and vent valves it will be possible to degas quite volatile mixes.

Once you are satisfied the material has been degassed close the vacuum isolation valve, open the vent valve and remove the chamber lid. You are now ready to use your degassed material. This degassed mixture is then poured into the mould taking care to minimise any trapped air.

When the mould has been filled it can be placed into the vacuum chamber and evacuate as before. This time there should be minimum air bubbles breaking the surface which was trapped in undercuts or from the surface of the mould. Please again beware of boiling off the volatile components of the mixture and only a few seconds should be required at full vacuum.

The lid can be damaged or destroyed by such solvents. If the oil is particularly cloudy it is time for an oil change. Degassing processes are quite hard on vacuum pumps so change the oil regularly. Oil is a lot cheaper than a pump service, or a replacement pump! If changing the oil make sure the pump is hot before draining and NEVER use solvents of any kind as a flushing agent.

If you need to flush the pump use only clean vacuum pump oil. Air from mixing of resins and hardeners. Gases generated from the curing process. Larger, faster vacuum pumps. Ultimate final vacuum pump pressure Stirring under vacuum Volume of mixture being degassed.

Registered in England No.

Damaging silicone rubbers by evacuating air