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  • ABS (Acrylonitrile -Butadiene-Styrene)
    A Terpolymer produced from Acrylonitrile and styrene liquids and butadiene gas that are polymerize together in a variety of Ratios to produce the family of ABS resins.
  • Accelerated Ejection
    Rack and pinion linkages used to extend the reach of the ejector pins, so that the ejector pins move before the main ejector plate comes all the way forward.
  • Acetyl
    Rigid thermoplastic with properties similar to zinc, aluminum, and other metals. The molecular structure of the polymer is of a linear Acetyl, consisting of unbranched polyoxymethylene chains
  • Acrylic
    A synthetic resin from acrylic acid or a derivative thereof. Clarity is the property achieved at processing temperatures.
  • Amorphous Phase
    Devoid of crystalline (non-crystalline). Most plastics are amorphous at processing temperatures.
  • Angle Pin
    The fixed pin that engages a mold slide to move it when the mold opens and closes.
  • Annealing
    Heating, then gradually cooling a molded part to relax stress with no shape distortion.
  • Antimicrobial
    Antimicrobial Is anything that kills or inhibits the growth of microorganisms such as bacteria and fungi.
  • Autoclave
    Closed vessel for conducting a chemical reaction or other operation under pressure and heat.
  • Average Molecular Weight
    The molecular weight of a polymer determined by viscosity of the polymer in a solution at a specific temperature. This gives an average molecular weight of the molecular chains in the polymer independent of between weight average and number average molecular weight.
  • Back Pressures
    The resistance of plastic material to flow during processing due to its viscosity.
  • Balanced Runner
    For a molded part in a multi cavity mold to have a remote possibility of being the same the material should arrive at the gate in each cavity at the same time. As designers we were trained to use the geometrically balanced runner concept. This was achieved by making each path to the cavity the same distance from the nozzle to each cavity. This was thought to be the ultimate method for achieving perfect mold filling balance. Because we believed that consistent parts were desirable we forced this concept into our mold-quoting standard in mold making. We also quickly discovered that a balanced geometry could stay balanced if the cavity layout is mirrored. For example if a 2 cavity is balanced then a, 4 cavity is balanced and if a 4 cavity is balanced then an 8 cavity is balanced etc… for16, 32 and 64 and this is also why we quote molds in these cavitations. Then in some cases 3-cavity molds could be semi-balanced so we began quoting, 6,12,24, and 48 cavities.
  • Band Heater
    Electrical heaters that are round and used as the primary source of heat on barrels and nozzles of injection molding machines and extruders.
  • Boring Mills (Horizontal)
    These are used on any shape of work piece, holes, pockets, channels, ribs, slots, bores, counter bores, screws, and simple molding areas.
  • Boss
    Small projection from the part’s surface designed to add strength, facilitate alignment with another part during assembly, or permit attachment to another part.
  • Bottom Clamp Plate
    This is the bottom plate on the mold. This plate has knockout holes that interface with the press platens. It can also have clamp slots milled in to the sides if the rails are not recessed above.
  • Burn
    This is a result of having applied too much energy for too long to a polymer chain. Evidence of thermal decomposition is seen by some discoloration, distortion, or destruction of the surface of the plastic. Normally it is either black or brown depending in the plastic material type or additive and length of time the energy has been applied.
  • CAD (Computer Aided Design)
    The use of a computer to develop the design of a product to be manufactured. Also, the use of the computer to develop the design and necessary NC programs for use by the manufacturing equipment that will produce a product.
  • CAM (Computer Aided Manufacturing)
    The use of computers and computer technology to control, manage, operate, and monitor manufacturing processes.
  • Cast
    The action of forming an object by pouring a fluid monomer-polymer solution into an open mold where it finishes polymerization. Also, forming film and sheet by pouring liquid resin into a moving belt or roll.
  • Cavity
    This is the plate that has pockets milled to contain the cavities, or in the case of a round part the bored holes. It is located directly under the top clamp plate when the mold is in the storage position. When the mold is in the open position, it is the plate that will be visible when looking at the stationary side of the press. It also has the topside runner milled in if the mold is a cold runner. It will have waterlines drilled in it, contain the male taper lock pockets, and the leader pins holes. Vents and vent reliefs are usually located on the face of this plate for easy access for cleaning when required.
  • Cavity Plate
    This is the bottom plate on the mold. This plate has knockout holes that interface with the press platens. It can also have clamp slots milled in to the sides if the rails are not recessed above.
  • Center Gate
    In injection and transfer molding, the opening (gate) through which the plastic is injected and is positioned in the center of the cavity.
  • Clamp Slots
    The function of clamp slots is to provide a ledge for the clamp to hold the mold base in the press. The main problem we face with the clamp slots in the design of the mold is to make sure that mounting holes are in close proximity to allow the clamps to reach the edge of the slot. Platen holes used to be different in each press manufactures specification. The industry has now standardized these hole locations so molders can use presses made at different manufactures. Another problem we have had with clamp slots is how high they are in relation to the bottom and top of the mold. The designer must also take care to design the water patterns so the water lines do not fall in line with the bolt holes.
  • Clamp Tonnage
    Rated clamping capacity of an injection or transfer molding machine.
  • Clamping Area
    Largest area an injection molding machine can hold closed under full pressure.
  • Clamping Plate
    A mold plate fitted to the mold and used to fasten the mold to the machine.
  • Clamping Pressure
    Pressure that is applied to an injection or transfer molding machine
  • Clamshell Molding
    A variation of blow molding and thermoforming in which two preheated sheets of plastic are clamped between the halves of a split mold. Each cavity by vacuum in the cavity and injection air between the sheets.
  • CNC Lathes
    These are used for round work, diameters, grooves, faces, counter bores, and complex molding areas.
  • CNC Mills (Vertical)
    These are used for making blocks, second operations to rounds, holes, pockets, channels, ribs, slots, bores, counter bores, screws, and complex molding areas.
  • Cold Deck
    Material feed system designed into the injection mold to reduce material waste & improve part quality. Used interchangeably with Cold Runner.
  • Cold Runner
    Material feed system designed into the injection mold to reduce material waste & improve part quality. Used interchangeably with Cold Deck.
  • Collapsible Core
    This is an idea that has been revitalized for molding internal threads & undercuts. As illustrated below, a collapsible core is made of a central core pin surrounded by a slotted sleeve. The slotted sleeve is a spring steel that is cut form the impression of threads or undercuts on the inside of the plastic part. When the mold is closed, the center pin is pushed in, expanding the slotted sleeve to make its impression on the part. As the mold opens, the center pin extends, retracting the slotted sleeve. As the sleeve retracts, it clears the part’s internal cuts or thread. The part is then ejected normally. Collapsible cores can produce many parts that used to be impossible. Machines with collapsible cores can run faster since there is no waiting for a cam to slide or a threaded core to unscrew from the part. However, due to lack of cooling some material may run slower.
  • Compression Set
    This is a measure used to determine the ability of a material to with stand the forces required to seal under a given load at a set temperature for a set time and maintain its original shape.
  • Core
    Male part of a mold that shapes the inside of a molded part.
  • Core Pin
    The internal rod used to hold the inside of the preform (parison). This rod retains the resin during the injection molding steps as it is transferred through the cycle. The core is also the blowing pin where air or a blowing medium flows through the channels cut in the center of this core rod to expand the perform in the blowing mold.
  • Core Plate
    This plate retains the cores and generally has pockets built in them for the cores. It also has the bottom side of the runner milled in if the mold is a cold runner. It will have leader bushings, holes, and return pin holes.
  • Core Pulls
    Term used by press manufactures to describe hydraulically activated actions in a press that require either a sequential stop or start to make a multiple pate opening occur in the mold. Typically they are used to activate unscrewing hydraulic racks or internal pistons in a mold.
  • Crystalline
    A state of molecular structure in some resins denoting uniformity and compactness of the molecular chains.
  • Cycle
    One full sequence in a molding operation, from a point in the process to the same point in the next sequence.
  • Dowels
    These maintain the position of the component on a given plate. Only two dowels are used in a mold base plate to maintain the relative position. Using any more than two is usually a waste and creates alignment problems. While dowels are used to provide alignment, they are very limited in their effectiveness when it comes to controlling thermal expansion.
  • Draft
    The tapered design of a mold wall, which facilitates removal of molded part.
  • Drooling
    Leakage of resin from a nozzle or around the nozzle area during the injection step in injection molding. Also results in the escape of low viscosity resins from the nozzle.
  • Early Ejector Return
    Devices that use mechanical levers and toggles mounted on the mold to push the ejector plate back before the mold is fully closed.
  • EDM
    Acronym that stands for electrical discharge machine. These machines are used for any shape or work piece, and any form or part shape that cannot be machined with a round cutter.
  • Ejection
    Removal of the molded part from the mold by mechanical means or with compressed air.
  • Ejection System
    The hydraulic or mechanical system of the machine that is used to move the ejector plate.
  • Ejector Bottom Plate
    This plate is the back-up plate to all the of all ejector pinheads. It has stop pins mounted in it on the opposite side to keep the plate flat in the mold base. It has the knock out taps for the ejector rods, which requires it to be thicker than the retainer plate. It can also have water in it to keep the plate temperature stabilized with the rest of the mold base. If the mold base runs hotter than the ejector plate in a big mold the thermal expansion will cause the clearance to be too tight and the ejector pins will have premature wear and breakage.
  • Ejector Pins
    These pins are mounted in the ejector plate to eject the part. It is important to note that the standard size ejector pin tolerances are too loose to provide the proper clearance in crystalline material and must be selected so the ejector pin clearance is small enough to prevent flash in-between the ejector pin and the ejector pin hole.
  • Ejector Retainer Plate
    This plate has counter bores in it and through holes for the ejector pins. It can also have guided bushing holes and return pins. It will have tapped holes that attach the bottom ejector plate to it.
  • Fan Gate
    Opening between the mold runner and the mold cavity that has the shape of a fan. This shape helps reduce stress concentrations in the gate area by spreading the operating over a wider area.
  • Fill
    In injection molding, packing of a cavity or cavities to provide a complete part.
  • Flash
    Excess plastic around the area of the mold parting line on a molded part.
  • Flow
    During processing by injection compression, or transfer molding the flow of a plastic is a measurement of fluidity.
  • Flow Marks
    Distinctive surface marks caused when two flow fronts meet and weld together during molding.
  • Gate
    The opening through which the plastic enters the mold cavity.
  • Guide In Bushing
    The bushing into which the guide pin mates upon the closing of the mold.
  • Guide Pin
    A pin which guides mold halves into alignment on closing.
  • Guided Ejector
    This is a guidance system used to protect the ejector pin and holes from premature wear. It is comprised of a special bushing that aligns the two-ejector plates together and a leader pin that in mounted in the bottom clamp plate and into the support plate. The design of how this leader pin is mounted can be made very simple so the mold maker or the molder can disassemble the mold easily and put it back together without being a Houdini. By guiding the ejector plate it prevents uneven pressure and cocking of the plate, which ends up galling all the ejector pins. Many mold makers have this feature as an option on their quotation .In m experience it is well worth the money in a high production molds.
  • Hot Runner Molds
    Molds that have a melt conveying system that keeps the runner molten at all times in the mold. The method for doing this consists of a manifold (a larger piece of steel with holes that are in the center that allow the melt to be contained.) This large piece of steel referred to as a manifold is usually heated with cartridge heaters or cal rod heaters. You use the same rods in your oven at home. These heaters are controlled by the use of thermocouples hooked to controllers that turn the electricity to the heaters on or off depending on what the thermocouple signals the temperature of the block is.
  • Hot Runner Retainer Plate
    This plate typically houses the hot runner system if the mold has been designed for one. The plate is machined with a clearance of approximately .100 of an inch all around the manifold. It will have islands of steel left standing inside the milled clearance pocket for the hot runner system to prevent the bowing of the cavity plate.
  • Hot Sprue Bushing
    Mold Element that contains a heating element to keep the resin melt hot within the bushing. The bushing is inserted into the mold to provide a hot channel between the molding machine nozzle and the mold cavity.
  • HTV
    The LSR material used in molding is High Temperature Vulcanizing. This means that material is formulated to cure or vulcanize at a temperature from 275°F to 425°F. This is in contrast to what is called RTV (Room Temperature Vulcanizing) that is used in most house hold applications.
  • Hydraulic Clamp
    Used in a variety of molding and forming machines, hydraulic clamp consists of a high-speed variable hydraulic pump valving a fast cylinder. Cylinders can be single or combination units. The clamp closes the mold halves to form the part.
  • Improved inspection equipment brings increased efficiency to American Tool & Mold

    American Tool & Mold is pleased to announce that it has just acquired additional measurement equipment to ensure precise evaluation and inspection of parts. “The Mitutoyo Quick Vision system is miles ahead of our previous equipment. It has a number of features that are expected to result in great savings for the company,” according to Phil Gaitan, Director of Sales.

    The Mitutoyo Quick Vision APEX pro series has accuracy to (1.5+3/1000) microns. This rating is the top of the industry, exceeding the needs of the customer. The table has a movement of 15.75” x 15.75” and a height of 9.84” giving plenty of space to measure either single or multiple dimensions on multiple parts.

    The touch probe allows precise 3-D vision measurement of very complicated parts along all three axes simultaneously. By eliminating the need for manual, mechanical probes, human measurement and transcription errors are avoided and the inspection time is speeded up considerably.

    A key feature of the equipment is the integration between the probe and the software. During the measuring process, the Quick Vision system can automatically input data into the MeasureLink SPC software. This allows real-time data review, so technicians can immediately notify the production department if there is a dimensional variation. By eliminating the delay between measurement and interpretation, the production department can make immediate adjustments, resulting in less scrap and less wasted labor.

    Another feature of the Mitutoyo system is the ability to measure accurately even on transparent or mirrored surfaces. A pattern is projected onto the surface, allowing measurement from the projected pattern.

  • Injection Molding
    Injection molding is a repetitive process in which plastic is melted or plasticated and injected into a mold containing a cavity in the shape of the desired article. With thermoplastics the mold is kept at a temperature below the solidifying point of the plastic, causing the injected polymer to “freeze” thus forming the article. After cooling, the mold opens and the part is ejected.
  • Injection Pressure
    Pressure applied to the injection ram to force the plastic from the barrel and into the mold (measured in psi).
  • Insert Molding
    Process by which components, such as terminals, pins, studs, and fasteners may be molded into a part.
  • Isotropic
    The ability to react the same regardless of direction of measurement. Isotropic materials will react consistently even if stress is applied in different directions. Stress-strength ratio is uniform throughout the material.
  • Jetting
    Turbulence in the resin melt flow caused by undersized gate of abrupt change in cavity volume.
  • Jig Grinder
    These are used for making holes, counter bores, radial forms, tapered holes, and some outside diameters.
  • Knockout Bar
    A bar that holds and actuates ejector pin/pins in mold. Used in ejection of molded piece from the mold.
  • Knockout Pin
    A pin that ejects a molded piece from the mold.
  • Laminar Flow
    The movement of one layer of fluid past or over another layer without the transfer of material from one to the other. Laminar flow is achieved by solidifying the layer in contact with the mold surface. This acts as an insulating tube through which material can flow to fill the remainder of the cavity.This process is essential to mold surface duplication.
  • Leader Bushing
    A leader bushing is what the leader pins enter into that aligns the mold base halves. Leader bushings are easily replaced when they wear. The life of a leader bushing can be extended withthe proper amount of lubricant applied during the production run.
  • Leader Pins
    These are pins that go through the top clamp plate into every plate with one pin offset to keep the plate from being assembled incorrectly. The pins are also used to guide the mold back together after the mold opening during the cycle. The pins serve two purposes. One is to guide the mold back together without misalignment. Without them there could be a possibility that the core and cavity would hit upon closing and cause damage the steel. Leader pins also prevent the mold halves form being assembled 180 degrees. This is why the offset pin is used on what mold makers call the zero corner.
  • Lift Holes
    These are not just for lifting the mold into the press. The toolmaker needs to have lift holes in every plate so the mold plates can be handled safely when disassembled. Holes need to be located in such a manner that the mold will be as level as possible when it is being lifted into the press. It is wise to use the safety hoist style eyehooks rather than the eyebolt. The eye bolts will bend and the tensile strength is much higher.
  • Lifters
    Lifters are sometimes used as an alternative to cam actions. Usually the lifter concept is used where it is not feasible to have a cam. They are primarily used to allow the steel to be removed by the use of a cam action that slides the steel away from the plastic. There are few things that the designer must be aware of when using lifters: The top of the lifter surface cannot protrude into the wall section. It is a good practice to have the top of the lifter at least .003 below the wall section to insure there is no hang up when it is activated. The lifter should not pull the part over with its action and result in the part sticking. A protrusion in the non lifter area will usually help keep it for sliding the part over with it. There are many standard lifter designs that are that are available from mold component manufacturers Because lifters have a tendency to wear it is good practice to design a mold operation including standard components. These designs are mass produced and take into account the proper tolerances and steel selections to provide the mold with the maximum life.
  • LIM®
    Liquid Injection Molding (trade mark of Momentive Performance Materials). Used interchangeably with LSR.
  • Location Ring
    This ring is used to locate the front half of the mold into the press plate. This ring protrudes from out of the top clamp plate and actually guides the mold base into the press platen during setup.
  • LSR
    Liquid Silicone Rubber. Used interchangebly with LIM®
  • Manifold
    Configuration of piping which fiberglass impregnated with plastic resin would act as filament winding. The portion of an extrusion die that forms the hollow center in an extruded tube.
  • Manual Lathes
    These require an operator to control and are used for round work, diameters, grooves, faces, counter bores, and simple molding areas.
  • Manual Mills (Vertical)
    These are used for making blocks, second operations to rounds, holes, pockets, channels, ribs, slots, bores, counter bores, screws, and simple molding areas.
  • Material Kit
    LSR is a two component material that is delivered to the molder in 200L Drum (also called Drum Kit) or 20L Pail of both A & B components.
  • Meter Mix Machine
    Also called the Pumps. This is the pump system used to pump equal portion of both the A & B components through a static mixer and into the Injection Molding machine.
  • Mold Plate Sequencing
    This is used to allow steel cores to be removed in sequence to allow for undercuts to flex out of the mold with out shearing. The proper sequence must take place so the designer has several methods for insuring the sequence. Below are listed some of the most common methods. There are also standard sequencing mechanisms available from the mold maker by venders. These mechanisms come with the correct steel choices and proper steel selection for maximum life.
  • Mounting Holes
    Now that the holes in the molding plates have been standardized many molders are requesting that the molds be mounted in the press with bolt holes in the mold base that line up with the platen tapped holes. The designer must make sure that there is proper clearance between the mold base and the screw head to turn the Allen wrench. The hole must also have the proper clearance to allow the bolt to be inserted while the mold is closed. Many molds have been designed that do not allow for the Allen wrench to turn tightening the bolt.
  • O-Rings
    These are used to keep intersecting water lines from leaking between plates or components. 0-rings will become brittle after time and should be replaced periodically. The o-rings come in standard sizes and are very low in cost. When installed, a combination of o-ring grease and the o-ring groove construction prevents the o-rings from leaking. The process of installing o-rings in round cavity or cores in a mold base requires extra special care in to prevent shearing which leads to water leaks. This usually occurs in straight-line bores where the intersection of the connecting water line in the base comes through the cavities. A mold designer has several options in the design of the mold to prevent this potential problem. The stepped bore is the most popular way. This does add to the mold cost but in the long run will help in mold maintenance.
  • OD Grinder
    These are used for round work, diameters, grooves, angles, tapers, shoulders, and heels.
  • Orange Peel
    An uneven surface somewhat resembling that of an orange peel.
  • Packing
    Filling the mold cavity/cavities as full as possible without causing undue stress on the molds or causing flash to appear on the molding.
  • Pigment
    Colorant added into Silicone to produce a wide variety of colors.
  • Pinpoint Gate
    Gate in an injection mold that is approximately 0.030 inches in diameter. This small gate minimizes the size of the mark left on the molded part.
  • Pipe Fittings
    These are standard pipes that allow for quick disconnects. They are used to connect the hoses to the water manifold to the press. In some case quick disconnects are added to so the mold setting time is reduced. Care must be taken when using the quick disconnects so they do not impede the flow of the water. If the quick disconnect is smaller in diameter than the waterline the water flow is restricted and may result in a laminar flow that will reduce the effectiveness of the water cooling.
  • Pipe Nipples
    These extensions to the waterline from the component allow hoses or connectors to be added between the component and the plate. The mold set up department should make sure that the fittings do not restrict the water flow. Sometimes, inadvertently, the flow will be impeded the water flow and will become laminar, reducing the effectiveness of the cooling line
  • Pipe Plugs
    Pipe plugs are used to plug water lines that are drilled into plate components, cores and cavities. Typically the plugs sizes are 1/16 to % N.P.T. standard.
  • Projected Area
    This consists of the area of the part that faces you when you look inside a mold. One simple way to describe it is that if you were to shine light on the part the projected area would be the shadow. Once you calculate the projected area you can use a general rule of 3-ton/square inch calculation for most crystalline materials to calculate the amount of force the part has generated during the molding process. Calculating Projected Area: If a projected area of a part is 635 mm (25 in) and you use 3 tons per square inch you will need to generate 75 ton per part. If you have a four-cavity mold this would require a press that has 300 tons of clamping force. By stacking another mold on top the opposing forces would cancel out the force in one direction this allows you to add 4 more cavities in the press that would normally require 600 ton press. By reducing the press size the press rates for a 600-ton would be less than a 300 ton press thus reducing the overall cost to produce the product. Molder friendly Design Tip – When you need to calculate the projected area of a part that has an irregular shape you can lay the part on a 1″gridpaper and trace the part then count the squares that are filled up. Then count the ones that are half filled divide by two and add it to the amount of full squares. Then you should have a close idea of the projected area.
  • Prototype
    A model suitable for use in complete evaluation of form, design, and performance.
  • Pry Slots
    These are milled slots used to help the toolmaker disassemble the plate. The size of the slots will allow for most standard pry bars to be place between the plates and force the plates a part. Without the pry slots tool disassembly can be very difficult, especially when plates are doweled together.
  • Rails
    Sometimes the rails are part of the ejector housing. They are used support the mold on each side of the ejector plates. The mold identification plate is usually mounted on the side of the rail. Rest Buttons- Buttons used to support the ejector plate and keep it flat. They are usually 5/16 in diameter and are strategically placed under the return pins and in between the support pillars.
  • Retainer Rings
    These are used on round components such as stripper rings to keep the strippers in the plates from falling out. Care must be taken to make enough room in the counter bore to allow for the retaining ring to open up adequately during installation. The designer must also allow for access to for the retaining ring wrench to remove the ring when it is required to disassemble the mold.
  • Return Pins
    These are used to return the ejector plates to the home position to prevent damage to the cavity in case the ejector plates are inadvertently left forward when the mold closes. The pins on the outside corners ejector plate used to return ejector system so the mold closing action does not have the ejector pins striking the inside of the cavity. With today’s presses and the new standard press functions for low pressure close, this mold feature is practically obsolete.
  • Ring Gate
    Used on cylindrical shapes, this gate encircles the core to permit the melt to first move around the core before filling the cavity.
  • Runner
    The channels milled into a plate in an injection mold that allows material to flow from the machine nozzle to the cavity.
  • Runner Stripper Plate
    This part is used to strip the runner off the sucker pins.
  • Shipping Straps
    These keep the mold halve together when putting a mold in the press. If the straps are painted orange they will not be easily misplaced. The mold should also have mounting holes in the mold base to store the straps while the mold is in use in the press. This small oversight in the design can cost the molder time looking for the shipping straps when it comes to taking the mold back out of the press.
  • Shrinkage
    The decrease in dimension of a molded part through cooling.
  • Slides
    Moveable steel sections of the mold containing part of the cavity that are slid out of the way to allow the part to be removed.
  • Socket Head Screws
    This is the type of screw that is the most common method to hold plates and components in the mold base together.
  • Sprue
    The channel or feel opening for the passage of material from the nozzle of the injection molding cylinder to the runners of the mold. The plastic piece is formed in this channel.
  • Sprue Bushing
    This is a bushing that interfaces with the injection press nozzle and connects to the runner in the plate. The sprue bushing is considered the primary runner channel and will set the cycle if it is too large. It has a nozzle the radius to match the molding press injection unit. The sprue bushing that contains the first leg of the runner. The sprue bushing can cause some problems if the wrong orifice size is used. The orifice size should always be at least .015 more than nozzle orifice to ensure there would be no undercut. In addition the nozzle radius must match the sprue bushing radii. Failure to match these two surfaces can result in a nozzle leak at the press and phenomena called a beehive will form around the nozzle costing hundreds of dollars in ruined heater bands. Beginning size orifice is determined by the amount of cavities and the gate size used in the mold. A small effective radius gauge is a good investment in the technician’s toolbox that properly identifies the radii. The two most common nozzle radii is.5 or .75 radii. Misalignment of the injection unit with the mold can also cause problems. In the Avaya plant a “machinist” would fix this.
  • Sprue Gate
    The passageway through which the resin melt flows from the nozzle to the mold cavity.
  • Sprue Puller Pins
    These are the pins in the center of the mold used to pull the sprue away from the nozzle. They have an undercut just below the parting line that is used to ensure that the orifice of the sprue is pulled away. If the pin is too large it will cause the undercut to be larger than necessary and can increase the molding cycle because it must solidify before ejection.
  • Sprueless Molding
    Mold design in which the sprue and runner system is insulated from the hot mold to prevent heating of the thermosetting resin in the sprue and runner. May also be referred to as hot runner molding of thermoplastics and cold runner molding for thermoplastics.
  • Stack Mold
    This is a special mold construction that allows the mold to take advantage of opposing forces of projected area. If you are unfamiliar with how projected area us calculated let’s time here to explain, because it is this principle that gives stack molds their reason to exist.
  • Static Mixer
    This is a block mounted to the feed throat of the injection molding machine. It has several intertwining paths through which all streams of the final LSR product are forced. This action causes all the components of the final material to be mixed prior to entering the screw portion of the molding machine.
  • Streams
    All LSR’s are made of at least two streams. The A & B components are individually called this prior to entering the static mixer. Additional streams can be added as required to achieve the desired characteristics of the final molded product. Examples of this most commonly are pigments for color and oils for scent, Antimicrobial, as well as other applications.
  • Stripper Bolts
    These are used to limit plate travel. The length of the bolts is given from the bottom of the head to the end of the body. The tapped hole is always smaller than the body. The placement of the stripper bolt follows the same rules as the screws. The most common problem with stripper bolts that are used in plate sequencing is that they will frequently come loose and need to be tightened. The designer should be aware of this and try to place them as close to the outside edge for easy accessibility to the technician. The majority of mold crashes that have plate sequencing using stripper bolts come from neglect of the mold technician not checking the stripper bolts.
  • Stripper Plate Mold
    In the case of a typical stripper plate mold the ejector system would not be necessary. This would eliminate the need for a rails, ejector retainer plate, ejector bottom plate. The stripper plate is used to mount the stripper ring in the mold base. This plate is usually on top of the core plate and will have the leader pin and bushing guided to prevent premature wear on the stripper and cores.
  • Sucker Pin
    This is a pin with an undercut that is directly above a cold runner drop. It is used to de-gate the runner from the part. If the undercut is too sever the material will chip or flake and will lodge in-between the runner plate and cause damage.
  • Support Pillars
    These round ground posts are used to support the plate above the ejector housing. The functions of support pillars are to help prevent the plate deflection caused by injection molding pressure. Without this support along with thickness of the support plate the mold can bow under injection pressure and cause flash. When a mold has had some use the support pillars will hob into the plates and lose their effectiveness. As a result this usually shows up as flash in the center of the mold. They normally have a .002-inch preload to them to ensure that the support plate will not flex during use. They are most effective when placed in the center of the mold. Support Plate- This plate used to keep the core plate from deflecting during injection. This plate is usually the thickest plate in the mold base, because it has to keep the mold from flexing during injection. The unsupported side of the plate has the ejector plates space underneath it and can easily deflect if there is not enough thickness. It also provides a base for the cores to sit on and provides space to feed the water lines to the cores.
  • Surface Grinder
    This a machine with a rotating grinding wheel that is used to finish flat surfaces, forms, side walls, slots, shoulders, and heels. It primarily used for mold plates or finish grinding of hardened tool steel.
  • Taper Locks
    These guide the mold halves back together. They should be on the centerlines of the mold. Some locks do not have an angle and are straight. The designer should always take care to make sure that if the locks are on and angle they should be at least one degree less than any shut off between the core and cavity. Round taper locks are not as effective, but can be used if the plate temperatures between the two plates that are being aligned are the same. The only effective way of aligning plates that have different temperatures is with the straight locks.
  • Thermocouple
    A pair of wires of dissimilar metals or alloys, the two junctions of which produce a current when they are touching a surface that has heat energy. The net electromotive force, or current, is sufficient to drive a galvanometer or potentiometer and tell a correlation of how much heat is at the junction.
  • Three-Plate Mold
    A three-plate mold usually refers to molds that have a top gate. So, a simple two-plate mold with a top gate becomes referred to as a three-plate mold. The name three-plate is derived from the plate openings. There are two openings between the three plates: one to remove the runner and the other to remove the parts. Some novices get confused between the three plates and the stripper plate molds. This is because both of them use a stripping action. The three plate stripping action is only used to remove the runner while the stripper plate is used to eject the part. A drawing of the stripper plate is shown in the next section. A three-plate mold can be used for stripper plate or pin injection.
  • Top Clamp Plate
    This is the top plate of the mold when it is in the storage position out of the press. When it is in the press this plate will rest against the stationary plate. It has clamp slots milled into it or mounting bolt holes to retain the mold in the press during opening. The top clamp plate also retains the cavity blocks, locating ring, sprue bushing, and leader pins. It will typically also have water lines drilled into it and have the electrical box mounted to it if the mold has a hot runner system.
  • Transducer
    A force-measuring device. It has the characteristics of providing an output, usually electrical, which serves as the measurement of load, force, compression, pressure, and etcetera when placed along the sensitive axis of the force cell.
  • Two Component or A/B System
    Silicone is composed of two parts that mix together prior to entering the mold to create a chemical reaction allowing for vulcanization to occur. These components are mixed at a constant industry standard ratio of 1:1
  • Two-Plate Mold
    The two-plate mold is the most common type of injection mold. But, why do we call it a two-plate mold when it is obviously more than two plates? The reason it is called a two plate mold is because when it is opened there are two halves. The plates on the cavity side are bolted together and the plates on the core side are bolted together. This is the simplest construction and functioning type of mold. In the drawing below you will see that it has an ejector housing. Although the ejector plates move inside the housing, they are considered part of the two-plate construction.
  • Two-Plate Pin Ejection System
    This is one of the most commonly used ejection systems known. This is the most versatile type of system is because it is used on the all shapes of parts. While the two-plate system can be used on both the round and non-round parts, it is used more on non-round parts. Round parts will lend themselves more to a less expensive type of stripper ejection. The goal of any ejector system is to eject the part automatically without distortion. The placement of pins becomes important in design to minimize the potential for distortion. In more sophisticated parts this ejector system can be used in conjunction with a stripper plate or plate sequencing to enhance the ejection so no distortion will take place.
  • Unbalanced Runners
    In some cases the merits of a balanced runner do not add up to a cost savings. Pictured below is a runner from a mold we made for toy soldiers a long time ago. It is obvious that the runner is not even close to being geometrically balanced. The toy soldiers were attached at the end of each branch. If you were to carefully inspect each soldier you would see sink and non-fill on these plastic soldiers in various places. The toy industry used this unbalanced runner concept in molding plastic figures to help achieve a lower cost. The molding customer understood the real customer was probably going to be a little boy on a limited income (called weekly allowance), so they had to keep the cost down.
  • Undercuts
    International indentations or slide projections in the part that do not allow for normal ejection perpendicular to the mold face.
  • Unscrewing Molds
    Parts made from these types of tools are easily recognizable by the serrated edges of the round part. The main idea behind understanding how an unscrewing mold works is study the actual movements involved in the process of removing a closure from a bottle. When studying the motions used you will be surprised to learn that while you are turning the cap your hand will automatically rise up to the pitch of the threads. A cam action on the stripper bar must do the same thing in order for the part to be removed from the core. Unscrewing molds consist of a rack, motor or hydraulic cylinder and a gear rack. The stripper plate will need an outside mechanism to cam the stripper plate in at the same rate as the thread pitch. This keeps the pressure on the underside of the part so the teeth on engaged to keep the cap from rotating with the unscrewing core. Another feature the cam mechanism has that pushes the part of the serrations is a bump on the end of the cam bar that accelerates the stripper plate creating inertia that pushes the closure off the serrations. Unscrewing molds are routinely considered as a viable method of closure (Le. screw-on bottle caps, etc.) manufacturing. If you are looking at a closure and have ever wondered what kind of mold was used to manufacture it the serrations on the bottom of closure will reveal if a part has been unscrewed or stripped. Unscrewing molds typically will have a longer cycle time than a stripped closure mold or collapsible core mold, which may cause you to ask why any are made this way. There are Two Basic Reasons: Unscrewing molds are usually necessary when the thread profile and the material chosen cannot flex due to the lack of elasticity in the material. The closure is tightened to provide a seal that would be leak proof. The strip thread mold design is not robust enough to provide a leak proof result. There are Primarily Two Types of Unscrewing Molds: The first type is known as a reciprocating core. This type does not require the stripper action to take part in unscrewing. This type of unscrewing mold requires racks, gears and hydraulic cylinders. It also must have serrations along the parting line of the open end of the closure deep enough to keep it from turning while the core is unscrewing and retracting, yet shallow enough to allow easy ejection. The second type is known as unscrewing stripper mold. In this type of design the core does not reciprocate but simply turns. The outside cam lifter bar of the mold drives the stripper up at the same rate of the thread pitch. This design requires that hydraulic cylinder and the thread cores move simultaneously. If the thread pitch and the cam bar angels are not matched it will cause the threads to strip. Both types of molds require a hydraulic cylinder that has alignment coupler as well as gears, and gear racks. The hydraulic cylinder must be long enough to turn the core enough revolutions to complete the unscrewing action and should be in line with the pull direction for best operating characteristics. An alignment coupler must be used to prevent the force of cylinder from cocking the rack and binding the mold. The flow rate of the oil, along with the design of the cylinder is most important to determine the best operation. A cylinder that is too large will have slower operating speeds. A cylinder that is too small may not have enough force to operate the mold action. Remember also that the maximum speeds and forces will likely be different from one direction to the other. Conventional rotary core molds are known to have some significant disadvantages. In particular, these molds require rotary seals in order to provide cooling to the cores. These seals are prone to wear and leakage and require significant maintenance time. Further, rotary seals limit the size of cooling lines and result in slower cycle times. The tapers between a stripper plate and the core also tend to get worn quickly due to the core rotation. In response to molders cycle time and maintenance concerns, certain suppliers to the injection molding industry have developed patented technologies to improve unscrewing technology. Most recently, the patented “Rotating Ratchet Ring” system by Husky Injection Molding Systems was introduced using “dog teeth” imbedded into the part to rotate the part off of the core of the mold. The “ratchet ring or stripper ring” is rotated using a hydraulic cylinder driving pinion gears and in turn driving the ratchet ring. This system allows for stationary cores, improved cooling and virtually eliminates taper wear.
  • Vent
    These are small air passages between the parting lines of steel components that allow the gases to pass out of the mold. They are usually located at the end of fill. They have to be large enough to let the air and gas out yet small enough to retain the plastic without flashing. Vents near the gates are more likely to flash and are usually smaller as they have molten material near them. The flash point of Crystalline material is smaller than that of the amorphous materials. True crystalline material will flash in spaces of .0127 mm (.0005 in) while some amorphous materials will not flash at .0381 mm (.0015 in).
  • Wire EDM
    These are used on any shape of work piece, cutting with a wire while using the EDM process, and any straight or tapered walls going through the work piece.