How to Successfully Complete Customized Injection Molds?
Successfully completing customized injection molds requires Lean-production management throughout the entire process, from needs analysis and design development to manufacturing processes and trial molding.
As a professional manufacturer of customized injection molds and plastic products, KingSjeng has been successfully practicing full-process management.
The following are the key steps and highlights:
I.Pre-Project Requirement Communication and Evaluation
- 1.Clarify Customer Needs
- Product Function and Specifications: Obtain product drawings, samples, or detailed technical requirements (such as dimensional tolerances, surface roughness, material types, etc.), and clarify the usage scenarios (e.g., whether high temperature resistance or corrosion resistance is required).
- Mass Production Requirements: Confirm annual production volume, injection molding machine model (clamping force, injection volume), and evaluate mold life (e.g., expected number of production cycles).
- Special Requirements: Whether complex designs such as surface treatment (e.g., texturing, electroplating), slider/lifter structures, or multi-station rotating molds are needed.
- 2.Feasibility Analysis
- Process Evaluation: Use simulation software like Moldflow to analyze injection filling, cooling, and warpage risks, and determine if the product structure is suitable for injection molding (e.g., wall thickness uniformity, draft angle, gate location).
- Cost Budgeting: Calculate material costs (mold steel grades, such as H13, S136), processing costs (CNC, EDM, wire cutting), trial molding, and transportation costs, and provide a quotation plan.
- 3.Contract Signing and Project Initiation
- Define delivery cycles (typically 4-6 weeks, depending on complexity), acceptance criteria (e.g., first-article qualification rate, mass production stability), payment milestones, and intellectual property clauses.
II.Mold Design and Review
- 1.Product Design Optimization
- Collaborate with customers to optimize product structures, avoid design flaws (such as air traps, sink marks, weld lines), and reduce mold development difficulties.
- Example: Increase draft angles (usually ≥1°) for easy demolding and avoid right-angle corners to reduce stress concentration.
- 2.Mold Structure Design
- Parting Surface Selection: Determine the optimal parting surface based on product shape to ensure smooth demolding and no parting lines on the appearance surface.
- Gating System: Design the sprue, runner, and gate type (e.g., subgate, hot runner) to balance filling speed and pressure and reduce material waste.
- Cooling System: Adopt a circulating water channel design to ensure uniform mold temperature and shorten the molding cycle.
- Ejection Mechanism: Reasonably arrange the positions of ejector pins and plates to avoid product whitening or deformation.
- 3.Design Review and Confirmation
- Organize internal reviews (involving design, process, and production departments) to check structural rationality (e.g., slider stroke, cooling channel layout, etc.).
- Submit 3D drawings (STP/IGS format) and DFM (Design for Manufacturability) reports to customers for confirmation, and finalize the design after approval.
III.Mold Manufacturing and Processing
- 1.Material Procurement and Pretreatment
- Select high-quality mold steel and perform heat treatment (such as quenching and tempering) to improve hardness (HRC 48-52) and wear resistance.
- Example: Use S136 steel for cores and cavities, and mirror-polish them to Ra ≤ 0.05μm after heat treatment.
2. Precision Machining Processes
- Rough Machining: Use CNC milling to form the basic shape, leaving a 0.2-0.5mm finishing allowance.
- Finishing:
- Electrical Discharge Machining (EDM): Process complex cavities and textures (e.g., leather texture, etching).
- Slow Wire Cutting: Machine precision inserts and lifter holes with a precision control of ±0.005mm.
- Multi-Axis Machining: Handle complex structures such as multi-curved surfaces and inclined holes.
- Surface Treatment: Nit-riding to improve surface hardness or coating (e.g., PVD coating) to reduce friction.
- 2.Quality Control
- In-Process Inspection: Use a Coordinate Measuring Machine (CMM) to detect key dimensions after each process and record CPK values (≥1.33 is qualified).
- Assembly and Debugging: Simulate the mold-closing action to check the smoothness of slider movement and the fit of the parting surface (clearance ≤0.02mm).
IV.Trial Molding and Optimization
- 1.First Trial Molding (T0)
- Use the customer-specified material for trial molding and record process parameters (temperature, pressure, cooling time).
- Common Issues and Solutions:
- Flash: Check for mold wear or insufficient clamping force and correct the parting surface.
- Short Shot: Increase injection pressure or optimize gate size.
- Dimensional Deviation: Adjust mold tolerances or injection parameters.
- 2.Sample Delivery and Feedback
- Submit first-article samples to customers for testing (e.g., dimensions, mechanical properties) and modify the mold based on feedback (T1, T2… until qualified).
- Archive trial molding samples as a benchmark for mass production.
V,Acceptance, Delivery, and Mass Production Support
- 1.Final Acceptance
- Conduct on-site trial production for customers to verify continuous production stability (e.g., 300 consecutive molds with a yield rate ≥95%).
- Provide mold acceptance reports (including dimensional inspection reports, trial molding reports, and material certificates).
- 2.Delivery and Training
- Protect the mold with anti-rust treatment and wooden crates, and use appropriate transportation to deliver it to the customer’s destination.
- Train customer operators on mold installation, debugging, and daily maintenance, and provide operation manuals and a list of vulnerable parts.
- 3.Mass Production Follow-Up and After-Sales Service
- Conduct regular follow-ups to resolve sudden issues in mass production (e.g., mold wear, product variations).
- Provide free maintenance during the warranty period and develop long-term maintenance plans (e.g., comprehensive inspections every 100,000 molding cycles).
VI.Key Success Factors
- 1.Cross-Departmental Collaboration: Real-time progress synchronization among design, processing, quality inspection, and project management teams, using Gantt charts or MES systems to track milestones.
- 2.Digital Tool Application:Manage design changes through PLM systems and ensure process control at all stages via APQP (Advanced Product Quality Planning).
- 3.Supplier Management: Select reliable suppliers for mold bases and standard parts to ensure the delivery time and quality of purchased components.
As a professional manufacturer of customized injection molds and plastic products, KingSjeng systematically reduces mold development risks through the above processes, ensuring on-time and high-quality delivery of custom injection molds, meeting customer mass production needs, and enhancing long-term cooperation trust.