Producing Zero-Porosity Aluminium Supercharger Housings
Manufacturing Aluminium Supercharger Housings with Zero Porosity
Producing high-performance aluminium housings for aftermarket automotive supercharger systems.
Project Overview
For specialist automotive applications, superchargers are often installed as aftermarket performance upgrades. These systems require precision components capable of withstanding pressure and mechanical stresses while maintaining perfect sealing. Omnidex was asked to manufacture a series of aluminium housings for aftermarket supercharger systems designed for several vehicle models. Unlike large automotive production runs, the volumes for these aftermarket systems were relatively small—typically only a few hundred units per model. Because of these limited production quantities, the challenge was to develop a manufacturing method that delivered high-quality components while keeping tooling costs at a practical level.The Engineering Challenge
Supercharger housings must meet two critical requirements:
- Structural integrity under pressure
- Zero internal porosity
Even very small levels of porosity can cause problems in pressurised air systems, allowing leakage that reduces supercharger performance.
At the same time, the relatively small production volumes meant that expensive tooling solutions such as investment casting or high-pressure die casting were not economically viable.
A manufacturing approach was required that balanced:
- lower tooling costs
- good dimensional accuracy
- and absolutely reliable sealing performance.
Selecting the Casting Method
To reduce front-end tooling costs, the housings were manufactured using gravity casting in aluminium.
Gravity casting offers several advantages for medium and low-volume production:
- significantly lower tooling costs compared with die casting or investment casting
- good mechanical properties in aluminium alloys
- flexibility for complex shapes such as supercharger manifolds
However, gravity casting can sometimes produce minor internal porosity, which in many applications is acceptable but cannot be tolerated in pressurised supercharger components.
Addressing the Porosity Issue
To ensure the housings were completely sealed, a resin impregnation process was used.
After casting and machining, the housings underwent a specialised sealing treatment designed to eliminate microscopic porosity.
The process involved:
- Heating a specially formulated resin to the correct temperature
- Applying the resin to the internal surfaces of the casting under pressure
- Allowing the resin to penetrate any micro-porosity within the aluminium structure
Once the resin had filled the microscopic voids, the excess material was removed by suction or draining.
This process sealed the casting internally while leaving the external dimensions unchanged.
Pressure Testing
After the impregnation process, each supercharger housing was subjected to a pressure verification test.
The housings were heated to a controlled temperature and then pressurised to confirm that the components were completely sealed.
This final step ensured that every housing met the performance requirements necessary for supercharger operation.
Final Result
- reliable zero-porosity housings
- reduced tooling investment
- production suitable for specialist aftermarket automotive applications
The finished components provided the strength, sealing performance and dimensional accuracy required for supercharger systems.
Engineering Insight
This project demonstrates how the correct combination of manufacturing methods and secondary processes can provide practical solutions for low-volume engineering production.
- gravity casting
- precision machining
- resin impregnation sealing
- pressure testing
