New Product Development with Injection Molding: Design to Production

The design that wins internal approval costs three times the target to manufacture. This happens when design, tooling, and manufacturing aren’t aligned from the start. The most elegant product concept fails commercially if it can’t be produced at viable cost, and discovering this late in development wastes months of effort and significant investment.

New product development with injection molded components follows predictable phases. Success depends on engaging manufacturing expertise early, making informed decisions at each phase gate, and managing the transition from prototype to production systematically. Programs that treat manufacturing as an afterthought pay for that oversight in delays, cost overruns, and compromised products.

The Development Phases

Product development proceeds through distinct phases, each with different objectives and constraints.

Concept phase explores what the product could be. Multiple approaches are considered, rough feasibility is assessed, and promising directions are selected for further development. Injection molding considerations at this phase are high-level: Is molding the right process? What materials might work? Are there obvious manufacturing challenges?

Design phase develops the selected concept into detailed specifications. Part geometry is defined, materials are selected, tolerances are established, and assembly approaches are determined. Design decisions made during this phase largely determine manufacturing cost and feasibility. Early manufacturing input prevents designs that look good on screen but can’t be molded economically.

Prototyping phase creates physical parts for evaluation. Multiple prototype methods serve different purposes: 3D printing for form and fit, machined prototypes for material properties, and soft-tooled or bridge-tooled parts for manufacturing-representative samples. Prototyping validates design decisions and identifies problems before committing to production tooling.

Tooling phase constructs the molds that will produce parts. Tooling represents major capital investment with long lead time. Tooling decisions lock in part design; changes after tooling construction are expensive. Thorough design and prototype validation before tooling release minimizes costly tooling changes.

Qualification phase validates that production tooling produces acceptable parts. Dimensional verification, functional testing, and process validation all occur before production release. Qualification may reveal problems requiring tooling modification or process adjustment.

Production ramp scales from initial qualification quantities to full production volume. Ramp-up tests production systems at increasing volume, identifies capacity constraints, and verifies sustained quality capability.

Design for Manufacturability

Manufacturing expertise engaged early in design prevents costly problems later.

When to involve molding expertise is as early as possible. During concept phase, manufacturing input identifies which concepts can be molded economically. During design phase, manufacturing input guides geometry, tolerance, and material decisions. Waiting until design is complete to consult manufacturing expertise discovers problems too late for easy correction.

DFM reviews systematically evaluate designs for manufacturing feasibility and cost. Wall thickness uniformity, draft angles, undercut elimination, gate placement, and ejection approach all receive attention. DFM reviews identify problems while CAD changes are inexpensive; the same problems discovered during tooling tryout require expensive modifications.

Concurrent engineering integrates product design and process development. Design and tooling teams work together rather than sequentially. Tooling design begins while product design continues. This approach requires more coordination but compresses overall timeline and improves results.

Cost of late changes escalates dramatically through development phases. A design change during concept phase might take an hour. The same change during detailed design might take a day. During tooling, it might require weeks and thousands of dollars in modification. After production release, changes may be practically impossible. Early manufacturing engagement prevents late expensive changes.

Prototyping Strategies

Different prototype methods serve different purposes at different development stages.

3D printing provides rapid geometry verification at low cost. Concept models, ergonomic evaluation, and fit checks all work with printed prototypes. However, 3D printed parts don’t represent injection molded material properties, surface finish, or production accuracy. Using 3D prints for mechanical testing or production validation leads to incorrect conclusions.

Soft tooling produces parts in actual injection molding materials from simplified molds. Aluminum molds, silicone molds, or composite tooling can produce hundreds to thousands of parts. Soft-tooled parts provide better material representation than 3D printing but may not match production tooling precision. Soft tooling suits functional testing and limited market testing.

Bridge tooling produces production-representative parts in volumes supporting initial market launch. Single-cavity production steel tools, simplified multi-cavity tools, or dedicated bridge molds enable production before full-scale tooling completes. Bridge tooling accepts higher per-part cost for earlier availability.

Matching prototype method to objectives guides appropriate investment. Early-stage concepts need quick visualization, not production accuracy. Functional validation needs representative material properties. Market launch needs production-capable supply. Overspending on early prototypes wastes money; underspending on validation prototypes leads to bad decisions.

Tooling Development

Mold construction transforms design into production capability.

Mold design reviews verify that tooling will produce intended parts. Gate location, cooling layout, ejection approach, and steel selection all receive scrutiny. Review participants include product designers, mold designers, and process engineers. Issues identified during design review are far easier to address than issues discovered during tryout.

Construction monitoring tracks tooling progress against schedule. Regular updates from the mold maker surface problems early. Inspection at key milestones verifies that construction matches specifications. Waiting until mold delivery to discover problems wastes the time that monitoring would have provided.

T1 through production approval represents the tryout and refinement process. T1 (first tryout) produces initial samples. These samples are evaluated; problems identified drive modifications. T2 incorporates modifications and produces improved samples. This cycle continues until samples meet all requirements and production approval is granted.

Managing the approval process requires clear criteria and decisive evaluation. Ambiguous requirements lead to endless iteration. Samples that “almost” meet requirements lead to scope creep. Clear pass/fail criteria and disciplined evaluation keep tooling development on schedule.

Process Development

Robust manufacturing processes support consistent production quality.

Scientific molding approach develops processes through systematic methodology rather than trial and error. Process parameters are established based on material behavior, part requirements, and machine capability. Documented processes support consistent results across operators, machines, and time.

DOE for parameter optimization uses structured experiments to identify optimal settings and their sensitivities. Design of experiments methodology efficiently explores multiple variables simultaneously. Results quantify parameter effects and interactions, enabling robust process setup.

Process documentation captures everything needed to reproduce quality production. Machine settings, material specifications, quality requirements, and inspection methods all require documentation. Complete documentation enables process transfer between machines or facilities and supports troubleshooting when problems arise.

Process validation demonstrates that documented processes consistently produce acceptable parts. Validation runs at production conditions verify capability. Statistical analysis confirms that process variation fits within specification limits. Validated processes provide confidence in production readiness.

Production Ramp

Scaling from qualification quantities to full production tests the entire system.

Scaling from sampling to production reveals problems that don’t appear at low volume. Machine-to-machine variation, operator variation, material lot variation, and throughput pressure all emerge at production scale. Ramp-up provides opportunity to address these issues before full production commitment.

Capacity verification confirms that production resources can meet demand. Machine availability, labor availability, and auxiliary equipment capacity all require confirmation. Bottlenecks identified during ramp-up can be addressed before they affect delivery performance.

Supply chain readiness ensures material and component availability at production volume. Supplier qualification, inventory positioning, and logistics arrangements all require verification. Supply chain problems during ramp-up delay production and damage customer relationships.

Quality system activation transitions from development-mode oversight to production quality systems. Statistical process control, inspection procedures, and response protocols all activate during ramp-up. Quality system effectiveness at production volume and pace confirms production readiness.

Program Management

Successful programs require disciplined management beyond technical execution.

Timeline management tracks progress against plan and adjusts for reality. Regular milestone reviews identify schedule risk early. Contingency deployment addresses problems without requiring schedule heroics. Realistic initial planning with appropriate contingency enables schedule success.

Risk identification anticipates problems before they occur. Technical risks, supply risks, capacity risks, and market risks all warrant attention. Risk registers document identified risks and mitigation plans. Proactive risk management prevents crises.

Cross-functional coordination aligns design, tooling, manufacturing, quality, and commercial activities. Misalignment between functions creates delays, rework, and suboptimal results. Regular cross-functional communication and clear interface agreements enable coordinated execution.

Common Development Pitfalls

Understanding typical failure modes helps avoid them.

Underestimating tooling complexity leads to budget and schedule overruns. Complex geometries, tight tolerances, and demanding surface requirements all increase tooling cost and time. Early tooling estimates based on incomplete designs often prove optimistic. Conservative assumptions early in development prevent surprises later.

Insufficient prototype validation allows problems to reach production tooling. Rushing from concept to production tooling saves time initially but creates costly iterations later. Thorough prototype testing catches problems when changes are inexpensive. The cost of additional prototype cycles is typically small compared to production tooling modifications.

Unclear specification ownership creates gaps and conflicts. When multiple functions contribute to specifications without clear ownership, requirements may conflict or important attributes may go unspecified. Clear ownership of each specification element ensures completeness and consistency.

Optimistic scheduling sets programs up for failure. Schedules that assume everything goes right inevitably slip when reality intrudes. Realistic schedules with appropriate contingency enable reliable commitments. Aggressive targets that nobody believes undermine credibility and encourage gaming.

Late supplier engagement limits supplier contribution to execution rather than optimization. Suppliers engaged early can influence design for manufacturability, identify risks, and prepare for production. Suppliers engaged late must simply execute whatever design they receive, missing opportunities for improvement.

New product development success depends on early collaboration and disciplined execution. The injection molding process is well understood; program management failures cause most problems. Engaging manufacturing expertise early, validating thoroughly before committing to tooling, and managing the production ramp systematically transforms good designs into successful products.

Sources

• Product Development and Management Association. “New Product Development Best Practices.”
• Plastics Technology. “Design for Manufacturability.” https://www.ptonline.com/
• RJG Inc. “Scientific Molding for New Product Development.”
• AMBA (American Mold Builders Association). “Tooling Development Process.”
• Project Management Institute. “Program Management Standards.”