Complex Industrial Plastic Parts Made by Vacuum Casting

Nylon-Like PU Components with Deep Features and Multiple Machining Directions

Some industrial plastic parts are difficult to manufacture not because of their overall size, but because many functional features are concentrated into one compact component.
This project involved a custom industrial equipment part with several cylindrical interfaces, deep openings, reinforcing ribs, side-facing features, mounting areas, and significant differences in feature height.
The customer required approximately 20 parts for engineering evaluation in Europe.
If every component were produced through CNC machining, the same multi-side machining strategy would need to be repeated across the complete batch. For this geometry, that meant more setups, more repositioning, and more tool-access challenges.
We therefore selected vacuum casting using a nylon-like polyurethane (PU) resin.
The complex geometry was first established in the master pattern, transferred into silicone tooling, and then reproduced as a low-volume batch.
 

Project Overview

The Manufacturing Difficulty Comes from Direction Changes

This component contains several functional zones that cannot all be reached efficiently from one machining direction.
A tall cylindrical feature rises from the center of the part. Several lower openings are positioned around the base, while other features extend sideways or are partially surrounded by ribs.
This creates three practical CNC challenges.

Multiple Setups

Different features require access from different directions.
Machining the base does not automatically provide access to the side-facing structures or deeper cylindrical areas. The workpiece may therefore need to be repositioned several times.

Large Height Differences

The difference between the upper cylindrical feature and lower structural areas affects tool reach and machining strategy.
Longer tools may be required for some regions, while surrounding geometry can restrict the cutting path.

Restricted Tool Access

Ribs, deep openings, and adjacent structures can make certain surfaces difficult to reach without additional orientations or special tooling.
For one part, this is a machining problem.
For 20 identical parts, it becomes a repeated manufacturing-cost problem.
 

The Real Cost Is Often the Number of Operations

When sourcing a low-volume plastic part, customers often compare unit prices.
For complex geometry, that is only part of the picture.
A multi-axis machining route can involve:

• Fixture preparation
• Repositioning
• Datum control
• Additional toolpaths
• Longer cutting tools
• Operator handling
• Intermediate inspection

If the component needs several setups, those operations are repeated for every piece.
For this project, that repeatability of machining complexity was one of the main reasons to consider a different manufacturing route.
 

Moving the Complexity into the Master Pattern

Vacuum casting changes the manufacturing strategy.
Instead of machining the full complex geometry repeatedly, the effort is concentrated into one qualified master pattern.
The route becomes:
Complex Master Pattern
→ Silicone Tooling
→ Nylon-Like PU Casting
→ Repeated Components
Once the silicone mold captures the geometry, subsequent parts can reproduce the same cylindrical features, ribs, recessed areas, and height transitions without repeating the complete multi-direction CNC sequence.
This is where urethane casting can become useful for low-volume complex plastic parts.
The key benefit is not simply lower tooling cost.
It is the ability to shift repeated geometry from machining into temporary replication tooling.
 

Silicone Tooling for Difficult-to-Access Features

Silicone molds provide flexibility that rigid tooling does not.
For suitable parts, this can help reproduce certain local undercuts, projections, and multi-directional features while keeping the component as one integrated structure.
For this industrial part, mold planning needed to consider:

• Tall cylindrical sections
• Deep openings
• Reinforcing ribs
• Side-facing geometry
• Local projections
• Demolding direction

The mold split and release strategy therefore remained an important DFM consideration.
Vacuum casting may reduce repeated CNC operations, but it still requires thoughtful mold design to reproduce complex geometry consistently.
 

Why Nylon-Like PU Was Suitable

The customer required material behavior similar to nylon for the engineering evaluation parts.
A nylon-like polyurethane casting resin was selected to provide a practical balance of:

• Toughness
• Moderate flexibility
• Impact resistance
• Structural strength
• Good detail reproduction

This material was suitable for the customer's current evaluation stage and allowed the complex geometry to be reproduced through silicone tooling.
Nylon-like PU is not the same as production PA6 or PA66.
If later testing depends on specific nylon properties such as wear resistance, elevated-temperature performance, chemical resistance, or long-term loading, parts made from the actual specified production material may be required.
 

Why the 20-Part Quantity Matters

The quantity alone did not determine the process.
Twenty simple plastic blocks might still be ideal for CNC machining.
This project was different because the 20 components combined:
Multiple Machining Directions

• Deep Geometry
• Large Feature Height Differences
• Restricted Tool Access
• Repeated Identical Parts

That combination made repeated CNC machining less efficient.
Vacuum casting provided a practical manufacturing window between one-off machining and production tooling.
For the customer, the savings came from reducing repeated setup and machining work across the complete batch.
 

Parts for Engineering Evaluation

The approximately 20 components were required for the customer's product development work in Europe.
The purpose was to obtain physical parts that could be used for:

• Engineering review
• Assembly checks
• Installation evaluation
• Structural assessment
• Internal testing
• Design confirmation

At this stage, the customer needed more than one demonstration model, but the project did not yet require production tooling.
This is where low-volume urethane casting can provide value for industrial equipment development.
 

Choosing the Process Based on Geometry

This project demonstrates an important manufacturing principle:

The best process is determined by the geometry that must be repeated—not only by the quantity.
CNC machining remains the better choice when actual engineering material, tighter tolerances, or specific mechanical properties are required.
Vacuum casting becomes attractive when a low-volume component combines complex geometry, repeated setups, suitable tolerances, and acceptable simulated material properties.
For this project, those conditions aligned.

Vacuum Casting for Complex Industrial Equipment Parts

YS Precision supports vacuum casting and urethane casting for complex industrial equipment components and low-volume plastic parts, including parts with:

• Multiple feature orientations
• Deep recessed geometry
• Cylindrical interfaces
• Reinforcing ribs
• Large height differences
• Difficult CNC tool access

Send us your 3D CAD files, quantity, intended production material, critical dimensions, and testing requirements.
We can review the geometry and determine whether vacuum casting, CNC machining, or another low-volume manufacturing process provides the most appropriate route.
For complex parts, process selection should focus on how the geometry will be manufactured repeatedly—not simply how one prototype can be made.