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Manufacturing Materials for Custom Metal and Plastic Parts

Material selection connects product performance with a practical manufacturing route. SAMSHION helps engineers compare metals, engineering plastics, elastomers and process-specific materials for CNC machining, injection molding, sheet-metal fabrication, 3D printing, vacuum casting and related production methods.

  • Material selection reviewed with the manufacturing process
  • Metals, thermoplastics, elastomers and additive materials
  • Material certificates and inspection documentation when specified
  • Support from prototypes to repeat production
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Choose Materials by Manufacturing Process

A material cannot be evaluated independently of the process that will shape it. The same nominal polymer behaves differently when machined from stock, injection molded, 3D printed or cast in polyurethane. A wrought aluminum plate, an extrusion and a casting may share an alloy family but differ in temper, grain direction, porosity risk, achievable geometry and finishing response. Start with the process route, then compare the grades available for that route.

CNC Machining Materials

CNC machining accommodates the broadest range of solid materials. Common choices include aluminum, stainless steel, carbon and alloy steel, copper alloys, titanium, nickel alloys and dimensionally stable engineering plastics. Machinability, stock form, residual stress, tool wear, chip control and thermal stability affect both cost and dimensional performance.

Use CNC machining when the project needs accurate features, low tooling commitment, real engineering material, rapid design changes or quantities that do not justify a dedicated forming tool. Milled housings and plates may suit CNC milling, while shafts, bushings and rotational features may favor CNC turning.

Injection Molding Materials

Injection molding uses thermoplastic pellets, elastomers and selected filled or modified compounds. Resin choice influences shrinkage, flow length, wall design, gate position, warpage, mold temperature, drying, appearance and tooling wear. A commercial family name such as nylon or polycarbonate is not a complete specification; grade, reinforcement, additives, color and regulatory requirements should be stated wherever they matter.

Use molding when the design and quantity justify tooling and when repeatable molded geometry, integrated features and scalable unit production are important. Final resin selection should be confirmed before mold shrinkage and cavity dimensions are released.

Fiber laser cutting sheet metal profiles in the SAMSHION workshop

Sheet-Metal Materials

Sheet-metal fabrication depends on alloy, temper, thickness, grain direction, bendability, weldability and surface condition. Aluminum 5052, stainless steels, cold-rolled steels, galvanized sheet, copper and brass each behave differently during cutting, bending, hardware installation, welding and finishing.

Use sheet metal for enclosures, panels, brackets, guards, chassis and welded assemblies whose form can be developed from flat stock. The drawing should identify material and thickness, and it should distinguish general dimensions from post-bend or post-weld critical features.

3D printing process from design to finished component using additive manufacturing technologies

3D Printing Materials

3D printing includes several processes rather than one universal material system. Photopolymer resins, thermoplastic filaments, polymer powders and metal powders have different design rules, anisotropy, surface texture, thermal behavior and post-processing requirements. A printed material described as “ABS-like” or “nylon-like” should not be assumed to equal an injection-molded production grade.

Use additive manufacturing for rapid geometry validation, complex internal structures, low-volume parts and designs that benefit from tool-free production. Select the process and material together based on the test objective and final operating conditions.

Vacuum Casting Materials

Vacuum casting commonly uses cast polyurethane systems formulated to approximate selected characteristics of production plastics. It can reproduce color, texture and flexible or rigid behavior for small batches, but the cast resin remains a simulation material rather than the named injection-molding polymer.

Use vacuum casting for appearance models, assembly trials, exhibition samples and low-volume parts where tooling speed and cosmetic consistency are more important than exact production-resin equivalence.

Extrusion and Secondary Machining Materials

Aluminum extrusion is suitable for continuous profiles with a consistent cross-section. Alloy and temper influence extrusion pressure, mechanical properties, bending, anodizing and subsequent machining. Extruded profiles can be cut, drilled, tapped, milled, bent and finished to create production-ready components.

Use extrusion when a repeated cross-section can reduce material waste and machining time compared with removing the same geometry from solid stock.

Metal Materials

Metals are selected by more than strength. Density, stiffness, corrosion resistance, electrical and thermal conductivity, fatigue behavior, temperature exposure, magnetic response, weldability, formability, machinability and finishing compatibility should be considered together.

Aluminum Alloys

Aluminum provides a useful combination of low density, machinability, corrosion resistance and finishing versatility. The correct alloy depends on whether the part will be machined, bent, welded, extruded, cast or anodized.

6061 is a versatile machining and structural alloy. It is commonly considered for housings, fixtures, brackets, plates and general engineering components. It machines and anodizes well in appropriate tempers, but actual color and appearance after anodizing depend on alloy condition, preparation and process controls.

7075 is selected when higher strength-to-weight performance is needed. It is common in loaded fixtures, structural components and weight-sensitive parts. Corrosion environment, temper, stress-corrosion risk, stock availability and finishing requirements should be reviewed for the application.

5052 is widely used for bent and fabricated sheet-metal parts because of its formability and corrosion resistance. It is generally more appropriate for formed enclosures and brackets than for heavily machined prismatic components.

6063 is frequently selected for architectural and heat-management profiles where extrudability and surface appearance matter. Structural load, temper and post-machining requirements should still be verified.

Stainless Steels

Stainless steels combine corrosion resistance with different levels of strength, machinability, formability and heat-treatment response. “Stainless steel” alone is not a sufficient purchase specification.

303 is designed for improved machinability and is useful for precision turned or milled components where welding and maximum corrosion resistance are not the primary priorities.

304-family stainless steels are general-purpose corrosion-resistant choices for machined, formed and welded parts. Low-carbon 304L can be beneficial for welded fabrication, subject to the project specification.

316-family stainless steels offer improved resistance in selected chloride and chemical environments compared with 304. They are considered for marine, process, laboratory and demanding equipment applications, but suitability must be checked against the actual chemical and temperature conditions.

17-4 precipitation-hardening stainless steel is used when corrosion resistance and higher mechanical strength are both required. Heat-treatment condition must be stated because it directly influences final properties and machining strategy.

Carbon and Alloy Steels

Carbon and alloy steels provide strength, stiffness, wear resistance and cost efficiency across machinery, tooling and structural applications. Corrosion protection, hardness condition, welding and heat treatment should be defined rather than inferred.

Low-carbon grades are useful for fabricated brackets, frames, plates and general machined components. They are readily welded and commonly protected by paint, powder coating, black oxide, zinc plating or another specified finish.

4140 is considered for shafts, tooling, fixtures and loaded machine components that need a useful strength-and-toughness balance. Supply and final heat-treatment condition affect machinability and properties.

Tool steels such as A2, D2, H13 and related grades are selected for molds, dies, wear components and process tooling. Grade, hardness, heat treatment, dimensional change and finishing sequence should be planned together.

Copper and Copper Alloys

Copper alloys provide combinations of electrical conductivity, thermal conductivity, corrosion resistance, machinability and appearance.

High-conductivity copper is used for busbars, thermal components, electrodes and electrical interfaces. Its ductility and heat conduction require suitable cutting and workholding strategies.

Brass grades are used for fittings, connectors, decorative components and precision turned parts. Composition influences machinability, forming, conductivity, color and regulatory suitability.

Bronze families can provide bearing performance, corrosion resistance and wear behavior for bushings, sliding components and marine or industrial applications. Select the specific bronze grade around load, lubrication and environment.

Titanium Alloys

Titanium offers high specific strength and corrosion resistance but requires controlled machining, heat management and contamination practices. Grade 2 and Ti-6Al-4V serve different property and application needs. Any medical, aerospace or regulated use requires the appropriate material specification, traceability and customer-controlled acceptance requirements; the material name alone does not establish compliance.

Nickel Alloys

Nickel-based alloys are considered for heat, corrosion and high-stress environments. They generally involve high tool wear, slower material removal and careful process planning. Exact grade, condition, certification and required test documentation should be confirmed before quotation.

Engineering Plastics for Machining

Machined plastics can provide electrical insulation, low friction, chemical resistance, reduced mass or rapid access to functional polymer parts without a mold. They also react more strongly than metals to heat, moisture, residual stress, clamping and time-dependent loading.

POM offers dimensional stability, low friction and good machinability for gears, guides, spacers, housings and precision mechanical components. Homopolymer and copolymer grades differ, so the exact requirement should be stated when performance depends on grade.

Nylon provides strength, wear resistance and toughness, but moisture absorption can change dimensions and properties. Conditioning state and operating environment should be considered for close-tolerance parts.

PEEK is used where temperature capability, chemical resistance and mechanical performance justify a premium polymer. Grade, reinforcement, annealing history, stock form and application requirements affect machining and acceptance. Review the PEEK CNC machining guide for additional design context.

Polycarbonate is valued for impact resistance and potential transparency. Machining heat, internal stress, cleaners, coolants and polishing methods can affect cracking and optical appearance. Optical or cosmetic requirements require a defined acceptance sample or standard.

ABS is commonly used for prototypes, housings and general-purpose plastic components. Machined stock can support quick functional evaluation, but its behavior should not be assumed identical to an injection-molded grade or 3D-printed “ABS-like” material.

PTFE offers low friction and broad chemical resistance but is soft and susceptible to creep and dimensional movement. Fits and measurement conditions should reflect its material behavior.

Polyethylene and polypropylene provide low density and chemical resistance. Their softness, thermal expansion and tendency to deform under clamping can complicate tight-tolerance machining. For molded PP projects, material flow, shrinkage and living-hinge requirements should be reviewed through the injection-molding route rather than copied from machined stock behavior.

Injection Molding Resins

Injection-molding material selection begins with the complete commercial grade, not just the resin family. Reinforcement, impact modification, flame-retardant package, UV stabilization, release additives, colorants and recycled content can change processing and end-use performance.

ABS, polypropylene, polyethylene, polystyrene and related families cover many housings, covers, containers, clips and consumer or industrial components. Selection should consider impact, stiffness, chemical exposure, assembly, finish and operating temperature.

Polycarbonate, PC/ABS, POM, nylon, PET, PBT, PPS, PEEK and other engineering resins are used when dimensional, thermal, wear, flame, chemical or mechanical performance exceeds general-purpose requirements. Drying and processing windows differ substantially by grade.

Glass fiber, mineral, carbon fiber or other fillers can raise stiffness, dimensional control or heat performance while increasing anisotropy, tooling wear and cosmetic sensitivity. Fiber orientation can influence shrinkage and warpage, so gate location and structural direction matter.

Clear polycarbonate, acrylic and other transparent materials require careful attention to resin handling, mold polish, gate and weld-line location, stress, dust and visual inspection. “Clear” should be translated into measurable or sample-based appearance criteria.

Thermoplastic elastomers cover a range of hardness, grip, rebound, sealing and overmolding behaviors. Shore hardness alone does not fully define performance. Adhesion to a rigid substrate, chemical exposure, compression set and color should be evaluated for the specific grade.

Specify resin manufacturer and grade when required, together with masterbatch or color standard, permitted substitutions, recycled-content restrictions and any relevant flammability, food-contact, biocompatibility or environmental documentation. SAMSHION will confirm what can be supported for the project; it should not be inferred from a generic material-family listing.

Sheet-Metal Material Selection

Sheet-metal material is inseparable from thickness and temper. A nominal grade that bends well in one condition may crack or spring back differently in another.

5052 and 3003 are common formed-sheet choices, while 6061 may be used where higher structural strength is needed but requires more careful bend planning. Grain direction, inside radius and temper influence cracking risk.

304 and 316 families are used for corrosion-resistant enclosures, panels, guards and welded assemblies. Surface condition such as 2B, brushed or polished should be protected and oriented deliberately when appearance matters.

Cold-rolled steel is widely used for painted or powder-coated brackets and enclosures. Galvanized sheet adds a protective zinc layer but introduces cutting, welding and finishing considerations. Coating condition at edges and joints should match the environment.

Copper and brass sheet are selected for conductivity, shielding, thermal performance or appearance. Bend direction, surface protection, joining and finish need early review because cosmetic damage is difficult to hide.

3D Printing Material Families

SLA and related photopolymer processes can provide fine detail and smooth presentation surfaces. Mechanical, UV, moisture and long-term thermal behavior depend on the selected resin and post-cure. Use test data for the exact printed material rather than a generic “ABS-like” label.

SLS nylon and related powder-bed materials support complex geometry without conventional support structures. Surface texture, porosity, dimensional behavior and dyeing or sealing options differ from molded nylon.

FDM uses deposited thermoplastic roads and is useful for fixtures, concept models and selected functional parts. Layer orientation and process settings can dominate strength and finish; bulk-resin properties alone are not sufficient.

Metal additive processes can create complex channels and topology that are difficult to machine conventionally. Powder specification, build orientation, support removal, heat treatment, surface finishing, density verification and critical-feature machining form one integrated process plan.

How to Select the Right Material

State what the component must carry, contain, guide, seal, insulate, conduct, protect or present. Functional statements are more useful than starting with a familiar grade.

Provide temperature range, chemicals, water or humidity, UV exposure, wear, sterilization, electrical requirements and expected service duration where relevant.

Identify mandatory properties, regulatory constraints and customer-controlled specifications separately from preferences such as color or a familiar material name. This allows practical alternatives to be evaluated without weakening critical requirements.

Walls, pockets, undercuts, draft, cross-section, assembly features and quantity determine whether machining, molding, fabrication, extrusion, additive manufacturing or a combined route is appropriate.

Apply tight tolerances only where function requires them. Plastics and thin sections can move with temperature, moisture and fixturing, so measurement temperature, restraint and datum strategy may be important.

Define as-machined condition, texture, gloss, coating, color, masking and cosmetic zones. The surface finishing services page explains how substrate and process affect available finishes.

State whether the order requires a certificate of conformity, mill or resin certificate, batch traceability, inspection report, first article report, coating certificate or third-party test evidence. Documentation should be quoted as a project deliverable rather than assumed.

Material Properties Engineers Should Compare

Compare stiffness, yield and tensile strength, impact behavior, fatigue, wear, hardness and creep against the real load case. Published values depend on specimen, direction, conditioning and test method.

Review service temperature, thermal expansion, thermal conductivity, heat-deflection behavior and thermal cycling. A short-term peak rating does not automatically establish continuous-service suitability.

Compatibility depends on chemical concentration, temperature, exposure time, stress and surface condition. Use supplier data and representative testing for demanding combinations.

Conductivity, insulation, dielectric behavior, ESD control, transparency, haze and color need grade-specific validation. Manufacturing marks, texture and coating may influence optical appearance.

Moisture absorption, residual stress, stock form, anisotropy, creep, thermal expansion and process shrinkage can change part dimensions. Stable design and inspection require these effects to be considered before tolerances are finalized.

Base material, stock condition, toolpath, mold surface, layer texture and coating preparation determine appearance. When cosmetic quality matters, use approved samples, controlled lighting and defined acceptance zones instead of adjectives alone.

Material Documentation and Quality Control

SAMSHION reviews material identification and inspection requirements with the drawing and purchase specification. The appropriate evidence depends on risk, industry, supplier route and customer requirements.

Incoming checks can include supplier documentation, material identification, dimensions, visual condition and other project-defined verification. Not every order requires the same testing plan.

Material certificates, resin certificates, certificates of conformity, lot records and test reports can be requested where available and specified. The required document type and acceptance criteria should be stated before production.

Dimensional reports, first article inspection, in-process records and finish certificates can support controlled production. Review available quality assurance and inspection systems when defining the documentation package.

No material substitution should be made where a controlled grade is required without authorization. If equivalent materials are permitted, define the property, standard and documentation basis for equivalence.

Frequently Asked Questions

Yes. Provide operating environment, loads, temperature, chemicals, quantity, tolerance, finish and any mandatory standard. SAMSHION can compare practical manufacturing options, but final design and regulatory approval remain with the responsible customer engineering authority.

No universal stock claim is implied. Availability varies by grade, form, condition, quantity and supplier. Current availability and lead time are confirmed during quotation.

Yes. Put the manufacturer, commercial grade, standard, temper or condition and permitted substitutions on the drawing or purchase specification. Restricted sourcing may affect price and lead time.

Certificates and traceability can be provided when specified and supported by the supply route. State the exact document requirement before quotation so it can be included in project scope.

Not necessarily. Stock production, molding orientation, reinforcement, moisture, additive process, layer direction and post-processing can produce different properties. Validate the material-process combination used for the final part.

Specify resin manufacturer and grade when required, together with masterbatch or color standard, permitted substitutions, recycled-content restrictions and any relevant flammability, food-contact, biocompatibility or environmental documentation. SAMSHION will confirm what can be supported for the project; it should not be inferred from a generic material-family listing.

Use the resin grade plus an approved masterbatch, color code or physical standard where possible. Also define gloss, texture, lighting and cosmetic acceptance because color perception depends on surface and geometry.

Send CAD, a drawing, quantity, material or performance requirement, finish, critical tolerances, operating conditions and required certificates or reports. If the grade is undecided, explain the function and constraints rather than leaving the requirement blank.