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Plastic Injection Molding

80–400T in-house — hard and soft plastics, P+R composite components

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Process Overview

Plastic Injection Molding

Plastic injection molding melts thermoplastic pellets and injects the melt under high pressure into a closed mold. The mold is cooled, the part solidifies, and is ejected. The process supports high-volume production of consistent, dimensionally stable plastic components.

SIKING's plastic injection capability exists primarily to support composite programmes — P+R (plastic plus rubber) keypads, silicone-on-plastic overmolding, and multi-material assemblies where the plastic substrate needs to be produced in-house. This is a complementary capability, not the core offering — SIKING's primary expertise is silicone.

  • In-house capacity: 80–400T injection moulding machines
  • Hard plastics: PP, PC, ABS, Nylon (PA)
  • Soft plastics: TPU, TPE
  • P+R composite keypads: plastic frame + silicone key assembly
  • Qualified partner extension for parts requiring tonnage beyond 400T
  • No hidden handoffs — partner identity disclosed on request
80–400T
In-house tonnage range
PP/PC/ABS
Hard plastic materials
TPU/TPE
Soft plastic materials
Plastic Injection Equipment
Equipment Specifications

Plastic Injection Molding Specs

ParameterSpecification
In-House Tonnage Range80 – 400 ton
Partner Extension (larger parts)Via qualified partner — disclosed on request
Hard Plastic MaterialsPP, PC, ABS, Nylon (PA)
Soft Plastic MaterialsTPU, TPE
Composite CapabilityP+R (plastic + rubber) composite keypads and assemblies
Primary Use CaseSubstrate for silicone overmolding; P+R composite components
ToleranceConfirm at DFM review per material and geometry
Integration Benefit

Why In-House Plastic Matters for Composite Programmes

Substrate Produced On-Site

For silicone overmolding programmes, the plastic substrate is the first part of the assembly chain. Producing it in-house means the substrate specification, dimensional quality, and surface preparation are controlled within SIKING's quality system — not a separate vendor's. Fit-up problems between substrate and silicone overmold are resolved at SIKING, not passed between factories.

P+R Composite in One Programme

Plastic + rubber (P+R) composite keypads require a rigid plastic frame and a silicone key insert bonded together. Both components are produced in-house at SIKING. The assembly is completed on-site. One purchase order, one quality system, one delivery — not a three-vendor coordination task.

Partner Extension — Disclosed, Not Hidden

For plastic parts exceeding 400T in-house capacity, SIKING uses a qualified partner extension. This is disclosed to the customer upfront — not a hidden subcontracting arrangement. The partner is included in the programme documentation, and SIKING remains accountable for the finished part quality regardless of where the substrate was produced.

Process Flow

Plastic Injection Molding — Step by Step

1

Material Drying

Thermoplastic pellets dried to specified moisture content. PC and Nylon are hygroscopic — drying is critical to prevent splay and silver streaks.

2

Injection

Melt injected under high pressure into closed, cooled mold. Gate and runner design per tooling specification.

3

Pack & Hold

Packing pressure applied after initial fill to compensate for shrinkage. Reduces sink marks and dimensional variation.

4

Cooling & Ejection

Part cooled to ejection temperature. Ejected from tool. Gate removed where applicable. Part dimensionally stable.

5

Inspection

Dimensional and cosmetic inspection per drawing. For P+R programmes: substrate inspected before silicone assembly begins.

Best Suited For

  • Plastic substrate for silicone overmolding programmes
  • P+R (plastic + rubber) composite keypads — plastic frame + silicone key
  • Hard plastic components (PP, PC, ABS, Nylon) for composite assemblies
  • Soft plastic components (TPU, TPE) where flex or grip is needed alongside silicone
  • Light guide plates and backlight panels for keypad backlighting systems
  • Housings and structural parts that form part of a silicone-containing assembly

Not Suited For

  • Very large plastic structural parts requiring tonnage above 400T in-house — discuss partner extension
  • Standalone plastic commodity parts with no silicone or composite element — SIKING is not a general-purpose plastics moulder
  • Optical-grade transparent plastics requiring Class A surface finish and optical clarity certification — discuss at DFM review
  • High-performance engineering plastics (PEEK, PPS, LCP) — confirm material capability at DFM review
Common Questions

Plastic Injection Molding — FAQ

Is SIKING a full-service plastics moulder, or is this a complementary capability?
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Complementary. SIKING's primary expertise is silicone — compression molding, transfer molding, and LSR injection. The plastic injection capability exists to support composite programmes, particularly P+R keypads and silicone-on-plastic overmolding. Customers looking for a dedicated plastics-only manufacturing partner should note that SIKING's plastic capability is optimised for composite and assembly programmes, not standalone plastic commodity production.
What is a P+R (plastic + rubber) composite keypad?
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A P+R composite keypad combines a rigid plastic frame (injection-moulded PC or ABS) with silicone key inserts bonded into the frame. The plastic frame provides structure, click feel, and dimensional precision; the silicone keys provide tactile feedback, printing surface, and environmental sealing. P+R keypads are common in remote controls, medical devices, and industrial panels where a high-end keypad feel is required. Both the plastic frame and silicone keys are produced in-house at SIKING and assembled on-site.
Who is the qualified partner for plastic parts beyond 400T?
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The partner identity is disclosed to customers on request during the programme setup phase. SIKING does not publish partner details publicly. What we confirm: the partner operates under a formal qualification process, work is tracked under SIKING's purchase order and quality system, and finished part accountability remains with SIKING. You are not placed in a direct relationship with the partner — SIKING remains your single point of contact.

Discuss Your Plastic + Silicone Programme

P+R keypads, silicone overmolding substrates, composite assemblies. Send drawings for DFM review and quotation.

Request Technical Review → All Capabilities