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Micro Parts

What is Micro Molding?
Micro parts generally weight below one gram and feature micro-sized structures measured in microns. Injection molding these parts presents a unique set of challenges for manufacturers. In addition to the quality of the plastic part, melt residence time is one of the most important issues for the production of parts in the 1-1000 mg range. The amount of time that melt is exposed to processing temperatures while passing through the barrel and the hot runner is critical to the integrity of the material. Micro parts present a variety of other challenges including metering, inspection, demolding, handling, and the effects of minute forces such as static load.     

MHS offers highly specialized runnerless systems for micro-injection molding along with comprehensive process analysis to guarantee the right melt channel sizing and optimized design for your plastic part.

micro molded plastic part
Direct gated 0.015 g PSU micro part for medical device with a 0.6 mm valve gate, production output of 300,000 parts per day with a 24 cavity Rheo-Pro® multi-tip hot runner


Our all new electro-pneumatic micro-injection molding machines offer unparalleled performance in an extremely compact, user friendly package. The M3 series features our patented ISOKOR™ technology, specifically designed to address the unique challenges of molding small, direct-gated plastic parts. From prototype, to low volume, to mass production - M3 molding cells deliver superior part quality, speed, and flexibility.

M3 injection molding machines offer a fast, seamless transition from protoype molding to high volume production of small to micro-sized plastic parts, using low cost cavity inserts

Multi-tip Hot Runners
Rheo-Pro® Multi-tip nozzles are a compact and cost efficient solution for small and micro molded plastic parts. M05 hot runner nozzles are available both as valve gate and thermal gate systems. Gates are arranged in clusters of 2, 3, 4, 5 or 6 tips per nozzle body.

Rheo-Pro® 4 drop multi-tip valve gate nozzle in a 32 cavity hot runner. M05 nozzles are available both as thermal gate and valve gate systems.

Direct Gated Micro Parts
Eliminating cold runners reduces waste in form of scrap material and leads to substantial cost savings.
Additionally, direct gating is extremely energy efficient and minimizes the waste that is often associated with molding micro parts, where the weight of the runner is multiple times the weight of the actual part produced.

Composite engineering resin (30% glass) fiber 40 mg micro part. Direct valve gating eliminates the traditional cold runner. The cold runner to parts ratio in this application is 10:1.



Learn more


M3 Micro Molding Machines
Rheo-Pro® N04 Nozzles
Rheo-Pro® M05 Multi-tip Nozzles
Rheo-Pro® M05VG Multi-tip Valve Gate Nozzles
Medical Molding



  Turn-key micro injection molding machines available featuring integrated ISOKOR™ hot runner technology  
  Specialized hot runner solutions for conventional injection molds also available  
  Compact nozzles for close pitch gating  
  Reduced melt residence time for sensitive materials  
  Reduced runner volume for exact part weight  
  Built for high temperatures and pressure  
  Special gating options for micro shots  

Case Studies


N04 Nozzles
The Rheo-Pro® N04 hot runner nozzle is ideal for direct gating small to micro sized plastic parts  (0.005 - 20 grams).  An 18 mm nozzle spacing, with valve gates or thermal gates, allows for compact multi-cavity molds.  Valve gating delivers high quality plastic parts with extremely clean gate marks of 0.7 mm - 1.0 mm diameter and zero gate vestige.

Rheo-Pro® N04 valve gate hot runners feature a 4.0mm melt channel and a long, slender nozzle body available in lengths from 50.0mm to 160.0mm

Melt pressure analysis for 32 drop hot runner system using N04 direct hot tip gate nozzles for 70mg clear polycarbonate micro parts for medical device




Medical devices
Circuit board
Small components
Optical Systems
MEMS (Micro Electro Mechanical Systems)
Drug delivery devices
Fiber optics
Insert molded parts
Two-shot micro molding


Clean Room Micro Molding Options

  • Optimized for class 10,000 cleanroom environments
  • Features as small as 2 microns
  • Part weights as low as .0001 grams
  • Repeatability of +/- 2 to 4 microns (.002mm – .004mm)

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Insert and Overmolding
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MHS is a global supplier of hot runner systems, injection molding machines, controllers, and engineering support for manufacturers of plastic parts.