Blog

Star Rapid’s blog aims to share our hard earned knowledge on manufacturing and product development. We hope these articles help you to optimize your product design and better understand the world of rapid prototyping, rapid tooling, 3D printing and low-volume manufacturing.

New White Paper: Surface Texutre
AJAX progress indicator
Search:

  • 2

  • 2K Molding
    A type of injection molding in which two resins with different properties are processed sequentially in separate cavities of a single tool.  

  • 3

  • 3D Printing
    Also known as additive manufacturing, this refers to the production of a solid object by sequentially building up 2D layers of printing substrate.  

  • a

  • A-Side
    The A-Side is often the cosmetic side of the part. This side of the part is usually formed by the cavity or A-plate of the mold tool.  
  • Additive Manufacturing, AM
    Also known as 3D printing, additive manufacturing involves the building of a three-dimensional object by the controlled deposition of two-dimensional layers of substrate. May also involve continuous, non-layering processes. Compare to subtractive manufacturing.  
  • AddSub®
    Star Rapid's exclusive hybrid service. This combines the flexibility of additive manufacturing with the precision of traditional subtractive production methods.  
  • Angle Pin
    A strategically placed inclined pin, designed to retract a sliding core in a plastic injection mold tool.  
  • Anodizing
    One type of surface passivation. An oxide layer on the surface of a part is created by replacing some of the surface molecules with ions from an electrolyte bath.  

  • b

  • B-Side
    The B-side is often the inside or non-cosmetic side of a molded part. This side is usually formed by the core or B-plate of the mold tool in injection molding or pressure die casting.  
  • Baffle
    Flat or corkscrew shaped blades of metal inserted into the coolant channels of a mold tool to create a return coolant circuit within that channel.  
  • Ball Nosed Endmill
    In machining, a ball nosed endmill has a semi-circular cutting edge of a single radii.  
  • Barrel (Molding Machine)
    Cylinder housing the screw and check ring of a plastic injection molding machine. The barrel is also heated to help melt the plastic resin within.  
  • Bosses
    Projections or protrusions in cast or injected molded parts.  
  • Bubblers
    Typically thin, hollow tubes that are fitted into drilled holes of an injection mold tool to supply coolant in narrow or hard to reach areas.  
  • Build Plate
    Platform used in additive manufacturing upon which the layers of the part are built.  
  • Bull Horn Gate
    A type of submarine gate which gates on a face formed by the parting line.  
  • Bullnose End Mill
    Similar to a standard endmill, these cutting tools have radiused corners of a known size.  
  • Bump Off
    A shallow undercut area of a molded part that is able to be formed without lifters, sliders or handloads.  

  • c

  • CAD
    Computer Aided Design. The use of computer software to create 2D and 3D digital models of an object in preparation for manufacturing.
  • CAM
    Computer Aided Manufacturing. Producing objects with computer controlled machine tools using digital data.
  • Cascade Gating
    A type of sequential gating using hot runners, in which a series of gates are automatically activated in succession to fill a mold cavity.
  • Cavity
    Depression in a die casting or plastic injection mold tool, usually on the fixed or non-moving side of the mold. Typically forms the outside, convex and cosmetic face of the part.
  • Check Ring
    Fitted on the end of the screw inside the barrel of a plastic injection molding machine, the check ring acts as a non-return valve allowing correct holding pressures to be reached and maintained.
  • Chip Size
    The size of the metal chips that are created during CNC cutting operations.
  • Clamp Force
    The amount of pressure applied between the 2 platens of a molding machine.
  • CMM
    Coordinate Measuring Machine. This is a precision CNC controlled measuring device. Using special probes this machine can access and measure part features to a very high degree of accuracy on multiple axes.
  • CNC
    Computer Numeric Control. The precise control of automated machine tools via digital instructions derived from CAD/CAM software.
  • Cold Slug
    Semi solidified plastic material formed at the nozzle opening, blocking the flow of material during plastic injection molding.
  • Cold Slug Well
    A trap placed opposite the sprue in an injection molding machine. Designed to capture a cold slug so that it does not interfere with the subsequent production cycle.
  • Compression Molding
    Type of molding in which the substrate is compressed between two mold halves, to be cured under heat and pressure into the final shape.
  • Conformal Cooling
    The cooling of a mold tool using internal channels created via 3D printing.
  • Cooling Time
    A waiting period for die casting or plastic injection molding, allowing the part to solidify within the mold so that it can be safely ejected from the tool without deformation.
  • Copolymer
    A polymer derived from two or more monomers.
  • Core
    One half of a typical plastic injection or die casting mold tool. This is the moveable, convex half which in turn forms a concave part surface.
  • Core Pin
    A separate, removable insert in a plastic injection mold tool. Used to form a hole, aperture or other feature requiring high precision, or in areas requiring molded features difficult to access by other means.
  • Cusp Height
    In machining, the raised areas between adjacent passes of cutters.
  • Cycle Time
    Production time required to complete one finished part in a molding operation and prepare for the next injection.
  • Cyclic Cooling
    An approach to mold temperature control that allows rapid switching between hot and cold circuits.

  • d

  • Date Marking
    Indexable inserts used to mark the date an item was injection molded.
  • Datum
    A reference point on one or more faces, surfaces or features of a part, from which all other dimensions are calibrated.
  • Debossed
    Letters, logos or other graphic marks molded into a finished part, set below the surrounding surface.
  • Delamination
    Surface defect of an injection molded part due to the presence of contaminants within the machine.
  • Dial Indicator
    A visual readout using a rotating dial mounted on a precision measurement gauge.
  • Diaphragm Gate
    A variant of the edge gate, a diaphragm gate is used to gate around the full circumference of an internal hole on an injection molded part.
  • Dielectric
    Insulating fluid such as de-ionized water, used during electrical discharge machining (EDM).
  • Dimensions
    Dimensions are measurable sizes of part features using standardized units.
  • Distortion
    A malformation of an injected molded part due to poor design or process control errors.
  • DMLM
    Direct Metal Laser Melting. A type of powder bed 3D metal printing using a laser to fully melt and bond successive layers of metal powder on a build platform.
  • Draft Angle
    An angle applied to the design of a surface or side wall of a molded part, allowing it to be removed from an injection mold tool without damage.
  • Dryer
    Heated chamber used to remove excessive moisture from plastic pellets of raw material before injection molding.
  • DWG
    From "drawing". A common CAD file format.
  • DXF
    Drawing Exchange Format. A common CAD file format.

  • e

  • Edge Gate
    In injection molding, edge gates fill the mold cavity at a location along the split line, usually leaving behind a rectangular witness mark.
  • EDM
    Electrical Discharge Machining. The removal of material from a workpiece using high-powered electrical current.
  • Ejection
    The forced removal of a cast or injected part from a mold tool.
  • Ejector Blade
    Square or rectangular pins of different dimensions strategically placed in the mold to push out or eject the formed part during plastic injection molding
  • Ejector Pin
    Round pins of different diameters strategically placed in the mold to push out or eject the formed part during plastic injection molding.
  • Ejector Plates
    Two-part platen system holding the ejector pins for plastic injection molding tools.
  • Electrode
    A sacrificial conductor, usually of copper, which discharges high powered electrical current to erode the surface of a workpiece.
  • Embossed
    Lettering, logos or other features raised from the surrounding surface.
  • End Mill
    A cutting tool used in conventional milling. End mills have a flat cutting surface and sharp corners. See ball nose cutters, bull nose.
  • Engraving
    Etching text, logos or other graphical features into a part face with an ultrasonically vibrating stylus.
  • Etch
    Selective patterning or erosion of the surface of a part or mold tool to create a textured effect.

  • f

  • Family Mold
    A multi-cavity mold that creates two or more dissimilar parts for a single assembly.
  • Fan Gate
    One type of edge gate in a plastic injection mold tool design, wider at the parting line of the tool halves.
  • FDM
    Fused Deposition Modeling. A variant of 3D printing using plastic filament which is heated to the melting point and ejected from a nozzle in successive 2D layers onto a build platform to create a finished 3D shape.
  • Fixture
    A clamp, vise or other device to hold a workpiece securely while it is being machined.
  • Flash
    In plastic injection molding, a thin residue of waste plastic extruded from between the halves of a mold tool along the parting line.
  • Flow Front
    The leading edge of molten plastic as it works its way through the mold cavity during injection. The front will be the first part to contact the solid walls of the cavity and hence to cool and solidify first.
  • Food Safe
    Plastic which has been approved for use in food storage or preparation.
  • Forced Ejection
    Ejecting a finished part from a plastic injection mold tool using undercuts instead of ejector pins.

  • g

  • G-Code
    Digital instructions, usually derived from a 3D CAD file, which control the precise tool path, speed and other customized parameters of CNC equipment.
  • Gas Trap
    Pockets or voids in a plastic injection mold tool that trap gas during an injection cycle, caused by insufficient venting.
  • Gate
    A channel in a mold tool allowing molten material to flow from the runner to the cavity.
  • Gate Freeze Off Time
    During a plastic injection molding cycle, the amount of time typically available for molten resin to fill a cavity before it begins to cool and harden.
  • GD&T
    Geometric Dimension and Tolerance. This is the industry-standard symbolic language for annotating physical features and allowable variations on engineering drawings.

  • h

  • Handload
    A manually placed and removed component to allow the molding of undercuts in a plastic injection mold tool.
  • Heel Block
    An angled face that engages with a matching angle on the back of a sliding core to hold it in place.
  • Height Gauge
    Measuring device used to determine the height of a feature relative to a flat, horizontal surface plate.
  • Homopolymer
    A thermopolymer resin derrived from a single monomer.
  • Hopper
    Drum or cylinder into which is loaded plastic pellets for injection molding.
  • Hot Runner/Manifold
    In plastic injection molding, this is a heated system of channels used to distribute molten resin from the machine nozzle to hot tip locations within a mold.
  • Hot Sprue
    A heated, tapered hole in a plastic injection mold tool that allows material to flow directly from the machine nozzle into the mold cavity.
  • Hot Tip
    Sliding cores in plastic injection mold tools that are actuated with hydraulic power. Compare to manual sliders.
  • Hydraulic Cores
    Sliding cores in plastic injection mold tools that are actuated with hydraulic power. Compare to manual sliders.

  • i

  • IGES
    Acronym for Initial Graphics Exchange Specification. This is a CAD file format for 3D data.
  • In Mold Labeling
    Date stamps, material codes or other information applied to a part during the molding process via customized molding inserts.
  • Infill
    During additive manufacturing, infill is additional material added between layers to fill any gaps or voids left by the printing process.
  • Injection
    Molten thermoplastic or thermoforming resin forced into a mold cavity under pressure.
  • Insert Molding
    Plastic injection molding around the circumference of a metal insert.
  • International Standards Organization
    Organization that establishes consesus-based, market-driven standards applying to a wide variety of industries and services.

  • j

  • Jetting
    An injection molding defect that causes snake-like lines on the surface of a molding. Often caused when material leaves a smaller gate at high velocity directly into a thick section of the part or cavity.

  • k

  • Knock Backs
    A pin inside the plastic injection mold. After the mold is closed, it maintains a consistent gap between the cavity and core which is filled with resin during injection.

  • l

  • Lathe
    Machine tool for creating round profiles and cavities with concentric or rotational features.
  • Layer Height
    Average thickness of a deposited layer of substrate in additive manufacturing.
  • Line of Draw
    Main direction of motion for opening/closing the halves of a casting or injection mold tool.
  • Live Tooling
    Rotating cutting tools mounted in a lathe or turn mill tool turret for CNC machining.
  • Living Hinge
    A plastic hinge formed by exploiting the ability of some plastics to bend repeatedly without breaking.

  • m

  • M-Code
    Machine language for programming auxiliary functions in CNC machine tools. See also G-Code.
  • Master Batch
    Heavily pigmented plastic resin used to add color for plastic injection molded parts.
  • Melt Temperature
    Temperature at which plastic resin achieves a liquid or molten state and can therefore be molded.
  • Metal Safe
    Deliberately making some high-precision metal parts in mold tools oversized, so they can later be machined down to final dimensions.
  • Micrometer
    Precise measuring tool providing graduated measurements calibrated in microns.
  • Mill Turn
    A lathe that is fitted with live tooling enabling milling operations to be carried out on turned components.
  • Modular Unit Die
    A holding fixture of standard size which acts as a base for securing mold tools in a plastic injection molding machine.
  • Mold Base
    Custom core/cavity mold tools are made to fit inside of a mold base, which in turn is placed inside a plastic injection molding machine.
  • Mold Locks
    Precision machined tapered features on mold tools with male and female halves.
  • Mold Temperature
    Optimum temperature of a plastic injection mold tool based on the resin compound being molded.
  • Molding Cycle
    A molding cycle is composed of the following steps: Close, Inject, Pack, Cool, Open, Eject and Close.
  • Multi Cavity
    A pressure die casting or plastic injection mold tool with multiple cavities, for creating more than one part in a given cycle.

  • n

  • Nominal
    Of or pertaining to the precise numerical value of a dimension. Usually taken as the reference dimension from which allowable deviation must be made in most processes.
  • Nozzle
    Fitting in a plastic injection molding machine, used to eject molten resin from the barrel into the mold.

  • o

  • O-Ring
    A soft elastomer seal with a circular cross-section.
  • OES
    Optical Emission Spectroscopy. A method of positive material identification (PMI).
  • OMOM®
    One Man One Mold. Star Rapid's proprietary service for fast-turnaround tools created by a single master craftsman.
  • Outsert Molding
    Method of plastic injection molding in which the molded material is formed inside of a metal fitting. Compare to insert molding.
  • Overmolding
    An injection molding technique that allows a second injection cycle to mold plastic on top of an already molded base material.

  • p

  • Packing
    In plastic injection molding, a secondary application of pressure to a filled mold to ensure full part density and close dimensional tolerances.
  • Parting Line
    The parting line is the physical break or split between the two halves of a plastic injection or pressure die casting mold.
  • Pigment
    Coloring agent used in plastics, paints, and other raw materials.
  • Pin Gauge
    Precision ground, hardened metal pins of known diameter and tolerance used for measurement.
  • Pin Push
    A defect in plastic injection molding that usually presents as stress marks on the A-surface of the part directly opposite the ejector pins.
  • Plastic Injection Molding
    Manufacturing process using thermoforming plastic resin injected under pressure into the empty cavity of a mold tool to make multiple copies.
  • Platten
    The large fixed and moving plates in an injection molding machine. The mold halves are clamped to these plates.
  • Positive Material Identification
    PMI. The process for accurately identifying metal and plastic material by directly analysing its molecular or chemical composition and comparing the results against a known sample or database.
  • Pressure Die Casting
    PDC. Technique for creating solid parts by injecting molten metal under pressure into the cavity of a die casting mold.
  • Process Control
    Controlling the parameters of the plastic injection molding cycle to ensure optimal and repeatable part quality.
  • Push Backs
    A pin inside the plastic injection mold. After the mold is closed, it maintains a consistent gap between the cavity and core which is filled with resin during injection.

  • q

  • Quality Control
    Processes and procedures for measuring and recording numerical and subjective parameters affecting the visual and physical attributes of a manufactured part.
  • Quenching
    This is the rapid cooling of a workpiece to achieve specific material properties such as hardness. Normally part of the heat treatment process of metal used for mold tooling.

  • r

  • Resin
    Thermoforming or thermosetting plastic material used for injection molding.
  • Return Pins
    A pin inside the plastic injection mold. After the mold is closed, it maintains a consistent gap between the cavity and core which is filled with resin during injection.
  • Ribs
    Support structures in molded parts, usually placed at right angles to walls or bosses.
  • Rockwell
    An industry standard method for specifying material hardness.
  • Runner
    Feed channels cut into the faces of plastic injection molds, directing the plastic from the sprue to the gate.

  • s

  • Screw (Molding Machine)
    Long helical gear inside the barrel of a plastic injection molding machine. The screw helps to transport, heat and compress the resin for molding.
  • Short Shot
    An injection molding defect where material has failed to completely fill the cavity.
  • Shot
    Total volume of material injected into a mold cavity during one cycle.
  • Shot Weight
    The total weight of all parts, sprues, runners and gates produced in a single molding cycle
  • Shrink
    Decrease in volume of material when it transitions from a molten to a solid state. Varies according to the material type and part geometry. Fillers such as glass fiber can also affect shrinkage.
  • Shrink Fit
    Using heat to expand a collet, which then shrinks to form a tight mechanical fit with a cutting tool.
  • SLA
    Stereolithography. A 3D printing technique using ultraviolet (UV) light to successively cure layers of light-sensitive liquid polymer and fuse it into a 3D solid.
  • Sleeve Ejector
    A cylindrical ejector pin with a precision bore cut through the center allowing the sleeve to pass over a fixed core pin.
  • Slider/Sliding Core
    An automatic mechanism built into an injection mold to form undercuts or holes on the part. The opening and closing action of the mold pushes and retracts the undercut detail using angled pins and wedges.
  • SLS
    Selective Laser Sintering. An additive manufacturing process using a high powered laser to fuse successive layers of powdered metal or plastic into a three-dimensional solid.
  • Society of the Plastics Industry
    American trade and regulatory organization, recently changed name to Plastics Industry Association. They are responsible for creating a series of standard surface texture gauges for plastic injection molding tools.
  • Spark Erosion
    Method for removing small amounts of metal from a work surface through a series of high-energy discharges of current from a charged electrode within a dielectric or insulating bath.
  • Split Line
    Mark left on a molded part indicating where the two halves of the mold separate or the edges of a sliding core form an undercut.
  • Sprue
    The portion of the runner system between the nozzle of the injection molding machine and the runner system in the mold.
  • Sprue Bush
    A bushing in a mold which presses agains the nozzle of the injection machine to give passage to the runner system within the mold.
  • Sprue Puller
    An undercut opposite the sprue which causes the sprue to be pulled out of the sprue bush ready for ejection.
  • STL
    Stereolithography. Original CAD file format developed for the stereolithography additive manufacturing technology invented by Chuck Hull.
  • STP/STEP
    An ISO-standard data file format for creating and distributing CAD files.
  • Stress Marks
    Visual marks on an injected molded part where unequal heating and cooling during manufacture caused local distortion.
  • Stripper Plate
    Moveable plate used to push molded parts off of a mold core after injection.
  • Sub Gate
    A type of gate from the runner sytem into the component which goes below the parting lines, generally into a sidewall of the component, thus giving the advantage of automatic degating during ejection.
  • Subtractive Manufacturing
    Conventional manufacturing processes where successive amounts of material are removed from a workpiece with cutting, drilling or grinding tools. Compare to additive manufacturing.
  • Supports
    Load-bearing structures added to 3D printed parts to provide stability during the printing process.
  • Surface Coating
    An application of material on the surface of a workpiece to alter its physical, chemical or cosmetic properties.
  • Surface Finish
    The texture of a part's surface, which can be measured as a roughness (Ra) value. Also, a subjective determination of surface appearance.
  • Surface Plate
    A very flat and hard horizontal surface forming the base for measurement, tool setup and layout.
  • Surfometer
    Device for measuring surface roughness by dragging a sensitive stylus across the workpiece and recording the electronic wavelength so generated.

  • t

  • Tap
    Male cutting tool used to create internal threads.
  • Texture
    An organized and repeating pattern applied to the surface of a mold tool or finished part. Compare to Roughness.
  • Thermoplastics
    One group of moldable plastic resins which become molten when heated. Once set, thermoplastics can be re-melted and remolded with the addition of heat, so their physical state is said to be reversible.
  • Thermoset
    One group of moldable plastic compounds which are comprised of two or more constituents undergoing a chemical change during processing and molding. Once molded, the process is irreversible.
  • Three Plate Mold
    The third plate creates a parting line that is used for the runner system that allows the gates to be on the upper surface of the component away from of the core and cavity parting line.
  • Thumbnail/Toenail Ejector
    A round ejector pin that overlaps the side wall or edge of the component thus partially contacting the edge of the cavity.
  • Tolerance
    Allowable deviation away from a nominal value.
  • Transfer Molding
    A molding method using a pre-measured amount of solid or powder material that is placed in the transfer pot then forced from the transfer pot into a closed cavity and core area of a heated mold.
  • Turn Gate
    A rotating gate in a multi-cavity injection mold tool which is able to selectively close off different cavities.
  • Two Stage Ejection
    Ejection of a molded or die cast part from a mold tool, requiring more than one releasing step per cycle.

  • u

  • Undercut
    A hole or feature in a plastic injection molded part design that is not in line of draw. Typically an undercut will trap the part in the mold if undercut release mechanisms aren't used.
  • Undercut Release Mechanism
    A moving component in a plastic injection mold tool to allow the molding and subsequent release of the formed part at the undercut location.
  • UV Stable
    Plastic molding resin which is formulated to resist the deteriorating effects of UV light.

  • v

  • Vacuum Casting
    Method of creating copies of a master pattern, using liquid resin poured into a silicon mold which is then cured in a vacuum chamber.
  • Vacuum Fixture
    Holding fixture for CNC machining making use of vacuum pressure. Often used on thin, flat sheets of material where other clamping methods would be ineffective.
  • Vacuum Hardening
    Method of heat treating steel alloys within a vacuum chamber to prevent oxidation during the heating cycle.
  • Valve Gate
    A mechanical valve used in a hot runner system of an injection mold tool which closes off the gate between injection cycles.
  • Vapor Polishing
    Method of creating a very smooth surface on some transparent plastics to achieve optical clarity. The surface is melted with a reactive gas to cause it to flow and fill in minute cracks, scratches or voids.
  • VDI
    Society of German Engineers. Comparator templates used for grading EDM surface textures.
  • Vent
    Opening in a plastic injection mold to allow air to escape as the cavity is filled.
  • Vernier Calliper
    Precise measuring device comprised of opposing jaws which slide apart on a graduated beam to provide accurate measurement of length.
  • Vice
    Holding device which clamps the workpiece between opposing faces of jaws mounted on sliding screws to accommodate parts of different sizes.
  • Visual Quality Standard
    VQS. This is the criteria for standard visual inspection of a part.

  • w

  • Wall
    Vertical structures in molded parts, usually defining the exterior volume of a part cavity.
  • Warp
    Distortion of an injection molded or pressure die cast part caused by unequal cooling rates after molding.
  • Water Channels
    Fluid passages machined into die cast and injection molding tools, allowing the passage of coolant for temperature control.
  • Weld Line
    Visible mark on a molded part's surface, usually occurring around an obstruction such as a hole or cutout. Formed as a consequence of two flow fronts meeting during the injection cycle and cooling at differing rates.
  • Winkle Gate
    See Bull Horn Gate.
  • Wire EDM
    Electrical discharge machining, using a brass wire as a sacrificial conductor to cut precise shapes through hardened steels.

  • x

  • X-Axis
    One of three primary axes of movement in a three-dimensional X-Y-Z coordinate system. Generally assumed to be horizontal to the viewer's reference.
  • XRF
    X-Ray Fluorescence. Non-destructive analytical test for determining a material's composition by bombarding the surface with high-energy x-rays and reading the resulting emitted spectra, which is unique for all material types.

  • y

  • Y-Axis
    One of three primary axes of movement in a three-dimensional coordinate system. Generally considered to be vertical to the viewer's reference.

  • z

  • Z-Axis
    One of three primary axes of movement in a three-dimensional coordinate system. Generally considered to be towards or away from the viewer's reference.