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Precision Injection Molding of Plastic Parts

Accuracy and Reproducibility for Precise Parts

Shape accuracy, surface quality, component weight, or microstructure: precision injection molding has many faces. Plastic parts are entering new areas of application and the requirements are becoming ever more stringent. Suitable plasticizing and software solutions, as well as injection molding processes, let you elevate precision injection molding to a new level.

Your Advantages with our Precision Injection Molding Processes
Reproducible production thanks to optimum machine design
Picture shows the ENGEL smart-shut non-return valve

The basis for precision injection molding is the ideal design of the injection molding machine. To ensure the reproducibility of shot weights, precise plasticizing components such as non-return valves with smart-shut technology are used. In combination with electric injection units, the non-return valve meets your requirements for reproducibility and process control in the production of precision parts.

High melt quality as a prerequisite for precision injection molding
Picture shows a plasticizing screw by ENGEL

At ENGEL, precision in injection molding includes optimized plasticizing processes to reduce or completely eliminate internal part defects. The optimelt sequence program enables significant improvements in this area. The software-supported solution provides the user with a flexible modular system for the plasticizing sequence. It allows, for example, additional melt compression steps, therefore improving the plasticizing process.

Consistent part weight with digital assistance software
Image shows the iQ weight control software by ENGEL

The digital solution iQ weight control optimizes the injection volume during the injection molding process. This compensates for fluctuations in melt viscosity. iQ weight control reacts to external influences. The software ensures that the accuracy of the injection molding process is increased, and the part weight remains constant despite viscosity fluctuations. For molds with multiple cavities, iQ weight control is the right choice. It minimizes scrap due to overfilled or incompletely filled mold cavities.

High-quality surfaces thanks to multi-layer injection molding
Picture shows injection molding machine by ENGEL

With multi-layer technology, you can achieve an exact reproduction of the mold surface of your precision injection molded parts. It is mainly used to produce thick-walled lenses. The substrate is molded on the first machine, which is then overmolded on a second machine. The high precision of the finished part is defined during overmolding. Surface quality is guaranteed regardless of shrinkage. You achieve higher dimensional accuracy and beneficial optical properties.

Error-free microstructure for lowest shot weights
Picture shows an application of precision injection molding by ENGEL

The most striking example of precision requirements is micro injection molding. Part weights of a few thousandths of a gram and fine structures can only be achieved by high-precision machine movements. Our injection unit fills the gap for micro components and enables shot weights in the 0.3 gram range. Thanks to its precise design, the smallest microstructures for your parts can be produced without defects.

Surface details through heating and cooling in each cycle
Picture shows surface of a plastic part by ENGEL

Variotherm processes are well suited to avoiding larger or smaller weld lines. They are used for high-gloss effects on surfaces and ensure complete filling of mold cavities. The processes are based on pressurized water or heat transfer oils and allow hot-cold switching of mold areas. They improve the detail accuracy of parts in precision injection molding. Other variotherm processes are based on inductive heating solutions or the partial use of heating elements.

You need high injection molding precision to produce plastic products?

We support you with solutions for consistent part weight and fully formed surfaces – even for the smallest components.

Suitable Processes for Precision Injection Molding - an Overview

Process Product name Industry Application Procedure
Silicone processing / liquid injection molding LIM Various Primary optics LED headlights Processing of materials that crosslink only in the mold
Processing transparent materials optimelt Automotive & mobility Electronics Fiber optics, lenses of smartphone cameras Transparent components for optical applications
Thick walled lens production optimelt multi-layer Automotive & mobility Secondary optics LED headlights Transparent components for optical applications
Hot-cold switchover variotherm technology Automotive & mobility Electronics Achieving a high-gloss surface through alternating mold temperature control

Our Precision Injection Molding Processes
Image shows optical plastic part by ENGEL
New Software Reduces Micro-defects in Precision Injection Molding

For optical parts, avoiding internal defects during injection molding is extremely important. Small defects are the result of gases that get into the melt. We reduce the ingress of gases with software. The melt quality is increased.

Image shows Liquid Injection Molding for micro injection molding
Liquid Injection Molding for Micro Injection Molding

Precision injection molding for the smallest parts. Flexible and precise processing of liquid silicone, even for multi-component applications. Fully automated in a single step, no reworking necessary, and waste-free.

Your Advantages with the LIM Process
Can be Added on Existing Standard Machines

Our micro injection molding unit can be installed on a standard machine of the e-motion TL series within 20 minutes. Which means the machine can be converted for micro injection molding.

Precision through Servo-controlled Injection Unit

The all-electric injection unit is controlled by servo-motors. It features dynamic acceleration, high positioning accuracy, and reproducibility, and can be used in a variety of applications.

Integration into the Machine Controller

The micro injection unit is integrated into the machine control unit and has a maximum injection pressure of approximately 1000 bar. The injection pressure regulation is controlled via melt pressure sensors in the nozzle.


  • Precision and ergonomics

  • Low burr, no rework necessary and waste-free parts

Examples of Precision Injection Molding with LIM
  • LSR micro injection molding for near-weightless parts

    Part weight of only 0.0005 g. With our turnkey LSR micro injection molding production cell including tie-barless all-electric e-motion 30 TL LIM.

  • Precision Injection Molding for Producing FFP2 (N95) Masks with Replaceable Filter

    The FFP2 masks are manufactured on two tie-barless e-victory hybrid machines. With replaceable filter and soft silicone lip. For more comfort and an environmentally friendly product.

Image shows optical application in optimelt injection molding process
Process for Transparent Precision Parts

Transparent parts made of PMMA, PC or COC for optical applications. With the injection molding process for optical plastic products such as light guides or lenses, you produce molded parts that meet your requirements for outline accuracy. For optical applications, gentle processing of the melt and optimum self-cleaning behavior of the plasticizing components are important. Otherwise, material degradation could occur during plasticizing or in stagnation areas. This would result in defects that would be visible on the final part. ENGEL therefore offers special plasticizing components for transparent materials.

Your Advantages with the optimelt Process
Versatile Usage

Suitable for a variety of demanding camera and lighting optics applications.

Low Stress Parts

Precise injection compression molding of lenses and optical components.

Complete Mold Filling

Variotherm mold temperature control for best structure replication and increased accuracy.

Efficient Production thanks to Multi-Layer Technology

Plastic parts are manufactured layer by layer. The multi-layer method ensures accelerated cooling through layer build-up and high outline accuracy as well as shorter cycle times.

  • Highly efficient precision injection molding

  • Outline accuracy

  • Consistent component weight

  • More uniform shrinkage

Process for Thick-Walled Precision Injection Molded Parts

Process with two machines to produce multilayer lenses. The molded parts cool in air between the first and the second machine.

Video shows process for thick-walled precision injection molded parts >
Picture shows Head of Process Technologies & Digital Solutions at ENGEL Austria

Precision injection molding is not only defined by the size of a component. Often the details on the parts demand the highest accuracy from our machines. ENGEL accepts this challenge for all customer projects and offers customized solutions for every application.

Johannes Kilian, Head of Process Technologies & Digital Solutions at ENGEL Austria

Liquid Injection Molding - an injection molding process for producing elastic molded parts of two-component liquid silicone rubber

Polymethyl methacrylate, a transparent thermoplastic material

Polycarbonate, a thermoplastic material

Cyclo-olefin copolymer, engineering polymers

Liquid silicone rubber, soft liquid siliconeLiquid Silicone Rubber, weiches Flüssigsilikon.

Although the technology was developed specifically for lens technology, it is not only applicable to transparent plastics. The process can be used for any thick-walled components. The prerequisite is geometric feasibility and compatibility of the individual layers.

Discover More Injection Molding Processes for your Plastics Production

Over 20 proven injection molding processes for greater cost-effectiveness and different applications

Image shows surface finish of a plastic part by ENGEL

Surface Finish and Functionality

Injection molding process for demanding component designs with additional function integration

Image shows a transparent part by ENGEL

Optical and Transparent Parts

Injection-molded parts made of transparent plastics for a perfect view

Picture shows lightweight plastic part by ENGEL

Weight and Warpage Reduction

Injection molding process for lightweight plastic components to reduce weight and warpage of your plastic parts

Picture shows plastic part made of special material

Elastomers and Thermosets

A wide range of non-thermoplastic materials such as silicone, rubber, BMC or HTV can be processed by injection molding

Picture shows recycled material

Injection molding process for recycled materials

More safety and consistently high product quality despite recycled material.

Image shows plastic parts manufactured by ENGEL using injection molding processes

Overview of all injection moulding processes

Over 20 Proven Injection Molding Technologies for More Profitability

Markus Lettau

Molding Industry Business Advisor

+1 (717) 767 2016

Write us

The ENGEL team is happy to support you with extensive knowledge in the field of injection molding.

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