Glossary

General Terms  |  3D Printing  |  Cast Urethane  |  Thermoforming  |  Reaction Injection Molding (RIM)  |  Structural Foam  |  Injection Molding

A cylindrical protrusion on a molded part designed to receive a screw, fastener, or press-fit insert. Bosses must be designed with proper wall thickness ratios to avoid sink marks on the opposite surface.

The female portion of a mold that defines the outer shape of a plastic part. A single-cavity mold produces one part per cycle; a multi-cavity mold produces multiple identical parts simultaneously, improving throughput and reducing per-part cost.

The highest standard of exterior surface quality in plastic part manufacturing, requiring a flawless, paint-ready appearance with no visible defects such as sink marks, swirl marks, knit lines, porosity, or surface texture irregularities. Class A surfaces are typically specified for consumer-facing enclosures, and any part that will be painted, chrome-plated, or displayed prominently. Achieving a Class A finish often requires premium tooling with polished or textured steel molds, tight process controls, and secondary finishing operations such as priming, sanding, and multi-stage painting.

The male portion of a mold that forms the interior or recessed features of a part. The core fits inside the cavity when the mold closes, and the space between them defines the part geometry and wall thickness.

The total elapsed time for one complete production cycle, from injection or forming through cooling, ejection, and reset. Reducing cycle time lowers per-part cost and increases capacity. It is typically measured in seconds.

An engineering methodology focused on designing products and components to be assembled as easily, quickly, and cost-effectively as possible. DFA analysis evaluates part count, assembly sequence, fastener types, and component orientation to reduce assembly time, minimize the risk of errors, and lower labor cost. DFA is typically applied alongside DFM, while DFM ensures a part is easy to manufacture, DFA ensures the resulting parts are easy to put together.

An engineering discipline focused on designing parts that can be manufactured efficiently and cost-effectively. DFM reviews identify issues such as insufficient draft, non-uniform wall thickness, problematic undercuts, and poor gate locations before tooling is committed.

Steel pins built into the mold that push the finished part out of the cavity after it has cooled and solidified. Pin placement must be carefully planned to avoid cosmetic witness marks in visible or functional areas of the part.

Application of a protective copper substance to protect enclosed electronic products from electromagnetic interference (EMI). At Innova Engineered Plastics, we do all shielding in-house to ensure the highest quality.

Secondary operations performed on molded or formed plastic parts to achieve final geometry, fit, or finish. Common fabrication processes include CNC routing, drilling, cutting, bonding, welding, and assembly. Fabrication is often used to add features that cannot be formed in the mold or to join multiple components into a finished assembly.

A process in which a pre-formed component, such as a metal threaded insert, electrical contact, or structural reinforcement, is placed into the mold before material is introduced. The result is a single part with the insert permanently encapsulated, eliminating secondary assembly.

A substance applied to the mold surface to prevent the part from adhering and to ease ejection. Release agents may be external sprays applied between shots or internal additives compounded into the material itself. Excessive use can affect surface finish and secondary bonding.

A multi-step molding process in which a second material, often a soft thermoplastic elastomer (TPE) or rubber, is molded directly over a rigid substrate. Overmolding creates soft-touch grips, multi-color assemblies, and integral seals without adhesives or secondary assembly operations.

The fast fabrication of physical part samples directly from digital CAD data using additive manufacturing. Rapid prototyping enables design verification, fit-and-function testing, and customer approval before production tooling is committed, dramatically reducing development cost and time-to-market risk.

The raw plastic material (in pellet, granule, or liquid form) used as the feedstock for plastic manufacturing processes. Resin selection determines mechanical, thermal, chemical, and aesthetic properties of the finished part. Common resins include ABS, polycarbonate, nylon, polypropylene, and polyurethane.

A standardized scale for measuring the resistance of a material to permanent indentation. Shore A is used for soft, flexible materials such as rubber and elastomers; Shore D is used for harder, semi-rigid to rigid plastics. Lower numbers indicate softer materials on each scale.

A custom plastic machine enclosure that surrounds and covers the exterior of electronic or electromechanical devices. Such plastic custom enclosures are typically used in the medical, automation & robotics or test & measurement industries.

Addition of inserts, mesh, and other features to custom plastic enclosures. Ask how Innova Engineered Plastics process puts more detail in the original part reducing the requirement for secondary operations.

A category of plastic that softens when heated and hardens when cooled, a process that can be repeated without significant material degradation. Common thermoplastics include ABS, polypropylene (PP), polyethylene (PE), nylon (PA), and polycarbonate (PC). Thermoplastics can be recycled and reprocessed.

A category of plastic that undergoes an irreversible chemical cross-linking reaction during cure, forming a permanently hardened material that cannot be re-melted. Thermosets, including polyurethane, epoxy, and phenolic, offer excellent heat, chemical, and dimensional stability, but cannot be recycled by re-melting.

The permissible dimensional variation specified for a part feature, defining the acceptable range between minimum and maximum dimensions. Achievable tolerances vary significantly by process and material.

The molds, dies, fixtures, and forming tools required to manufacture plastic parts. Tooling represents the primary upfront capital cost in most plastic manufacturing processes. Tool material (steel vs. aluminum), number of cavities, and expected part volumes all drive tooling cost and lead time.

A feature, such as a groove, hole, or protrusion, that is perpendicular to the direction of mold opening, preventing straight ejection. Undercuts require side-actions (slides or lifters) in the mold, which add cost and complexity. Where possible, undercuts should be redesigned out during DFM.

Distortion of a finished part away from its intended geometry, caused by differential shrinkage due to non-uniform cooling, uneven wall thickness, or residual molding stresses. Warpage is one of the most complex defects to resolve and may require tool modifications, process changes, or material substitution.

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The overarching term for all processes that build parts by adding material layer by layer from digital designs, commonly known as 3D printing. Additive manufacturing enables complex geometry, internal features, and mass customization without traditional tooling, making it ideal for prototyping and low-volume production.

The maximum dimensions of a part or build envelope that a given 3D printer can produce in a single job, defined by the printer’s X, Y, and Z travel axes. Large parts that exceed the build volume must be split, printed as sub-components, and assembled or bonded after printing.

Temporary scaffolding generated by slicing software to support overhanging part features that cannot be built without a base beneath them. Supports are removed after printing, by hand, solvents, or water, and may leave surface marks requiring post-processing. Designing parts to minimize supports reduces cost and post-processing time.

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A low-volume manufacturing process in which liquid two-part polyurethane resin is poured or injected into a flexible silicone mold, cured, and demolded to produce parts that closely replicate the look, feel, and properties of injection-molded thermoplastics. Cast urethane is widely used for functional prototypes, bridge tooling, and short-run production.

The time required after pouring for the cast urethane to cure sufficiently to be safely removed from the silicone mold without distortion or tearing. Demold time ranges from minutes to hours depending on the formulation, wall thickness, and whether heat is applied to accelerate curing.

The instrument used to measure Shore hardness, and the term commonly used to describe the hardness of a flexible or semi-rigid urethane part. For example, a part may be specified as ’60A durometer,’ indicating a Shore A measurement of 60, a medium-soft elastomeric feel similar to a car tire tread.

The original part or model from which a silicone casting mold is made. Master patterns are typically produced by SLA, SLS, or precision CNC machining, and their surface quality directly determines the surface quality of every cast urethane part produced from the mold. Pattern finishing is critical to final part appearance.

A release agent applied to the interior surfaces of a silicone mold before casting to prevent the urethane from bonding to the mold and to ease part removal. Proper release agent application extends mold life and prevents surface tearing, porosity, or defects on the part exterior.

The flexible tooling used in cast urethane production, made by pouring liquid silicone rubber around a master pattern and allowing it to cure. Silicone molds can capture fine surface detail and textures, flex to release undercuts, and typically yield 20–25 parts, making them ideal for low-volume runs.

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A concave mold cavity into which the heated sheet is drawn. Female tooling produces better surface detail on the exterior of the part. Material distribution is thicker at the top and thinner at the bottom corners, which may require plug assist on deep parts.

A convex mold form over which the heated sheet is draped. Parts formed over a male mold have better detail on their interior surface. Material thins more at the top of the mold and is thicker at the base, the opposite distribution of female (cavity) tooling.

A thermoforming process that applies positive air pressure above the heated sheet to force it against the mold surface with greater force than vacuum alone can achieve. Pressure forming produces sharper corners, finer texture detail, and cosmetic quality approaching injection molding at significantly lower tooling cost.

A manufacturing process in which a flat thermoplastic sheet is heated to its forming temperature and then shaped over or into a mold using vacuum, air pressure, or mechanical assist. Thermoforming is cost-effective for large parts, enclosures, trays, and panels at low to medium production volumes.

A thermoforming process using plastic sheet or roll stock less to produce high-volume packaging such as trays, clamshells, blister packs, and lids. Typically a roll-fed, inline process where forming, trimming, and stacking happen in one continuous automated operation.

A heated plastic sheet is positioned over a mold and atmospheric pressure drives the sheet against the mold surface as a vacuum is drawn beneath it. Vacuum forming is economical and fast for large, relatively simple shapes.

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A process in which two reactive liquid components, a polyol (A-side) and an isocyanate (B-side), are mixed at high pressure in an impingement mix head and injected into a closed mold, where they react and cure into a solid polyurethane part. RIM produces large, lightweight, impact-resistant parts cost-effectively.

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A characteristic of structural foam in which the mold cavity is filled at significantly lower pressures than conventional injection molding. Low-pressure operation reduces mold and press wear, allows aluminum tooling, and enables very large projected areas that would require impractical clamp tonnage in standard injection molding.

A low-pressure injection molding process in which a blowing agent is introduced into the thermoplastic melt to create a cellular (foam) core surrounded by a dense, solid skin. The low injection pressure (200–500 psi vs. 10,000–30,000 psi for standard injection molding) enables large parts with reduced clamp force and lower tooling cost.

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The force exerted by the injection molding machine to keep the mold closed against the injection pressure of the melt. Measured in tons, required tonnage is calculated from the part’s projected area and the material’s pressure requirements. Insufficient tonnage causes flash; excessive tonnage can damage the mold.

A mold with multiple cavities that each produce a different part, typically a set of related components, in the same shot. Family molds reduce tooling cost but can be challenging to balance, as different cavity sizes may fill and pack at different rates.

A manufacturing process in which thermoplastic resin is melted and injected under high pressure into a closed mold cavity, where it cools and solidifies into the desired shape. Injection molding is ideal for high-volume production of complex, tight-tolerance parts with consistent quality and fast cycle times.

A mold containing two or more identical cavities that produce multiple copies of the same part in every injection cycle. Multi-cavity tooling increases output and reduces per-part cost but requires higher upfront tooling investment and more complex runner balancing.

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