Fuel injection systems use high pressures to deliver precisely calibrated quantities of gasoline or diesel. A defect in any injection system component could result in fuel spraying over a hot engine, with catastrophic consequences.

To avoid this kind of scenario, investment casting foundries producing automotive components adhere to strict Quality Assurance and Quality Control processes. This blog provides an overview of the approach taken and tools used by Impro. For more detailed information, readers are invited to contact us directly.

Investment Casting for Automotive

Investment casting produces accurate, complex metal parts that need very little finish machining. Most metals can be investment cast, although more reactive alloys benefit from being cast under vacuum.

Investment casting involves first molding a wax pattern of the part to be cast. This is coated in a ceramic slurry that dries to form a hard shell. The wax is melted out and molten metal poured into the cavity. Hollow regions in the cast part are formed by placing soluble cores in the wax pattern which are subsequently washed out.

Automotive applications of investment casting include:

• Fuel injection system components
• Precision engine components (rocker arms, for example)
• Housings, as required for exhaust gas recirculation
• Turbine scrolls for turbochargers
• Hydraulic system components

Ensuring Defect-Free Production

Long ago, manufacturers relied on inspection to control product quality. The problem with this is that it still allows production of defective items. This is addressed through Quality Assurance (QA). QA is the discipline of implementing and operating systems that prevent defects.

Leading investment casting foundries like those Impro runs, operate Quality Management Systems (QMSs) that apply QA principles. However, with a process as complex as investment casting, it’s just about impossible to anticipate and prevent everything that could go wrong, so Quality Control (QC) remains an important tool.

Quality Assurance

In the automotive industry, QA is built around Advanced Product Quality Planning (APQP). This is a structured approach to ensuring robust design and manufacturing processes are in place. By standardizing how each job or activity is carried out, variability is reduced and nothing is overlooked.

APQP uses the Production Part Approval Process (PPAP) to verify the plant is capable of producing what the customer needs, at the rate required. PPAP has 18 elements covering the activities required to design a part and put it into production. This includes using Failure Mode and Effects Analysis (FMEA) to identify every possible opportunity for errors or mistakes, and put preventive measures in place.

Automotive OEMs typically partner with their suppliers on APQP and PPAP, but independent certification of the QMS provides additional confidence in the integrity of the system. The QMS used at Impro has been audited and certified as complying with the automotive industry standard, IATF 16949.

Quality Control

Inspection is a core element of PPAP, and remains important after a product or part enters production. Impro verifies the accuracy and integrity of parts produced by investment casting in two ways.

Dimensional inspections are carried out on calibrated equipment used in controlled environments. Many parts are inspected on coordinate measuring machines (CMMs). A CMM is a multi-axis machine that performs a series of high-precision measurements, and is particularly useful for quantifying the geometric relationships between complex features.

Defect detection is performed by visual inspection, with crack detection tools, and by x-ray. X-ray is especially important for highly-loaded parts where internal flaws could lead to failure in-service. Impro uses automated x-ray equipment for throughput speed and consistency of results.

Quality Investment Castings For Automotive Applications

Investment casting is a repeatable and cost-effective process for producing complex metal parts. It can simplify assemblies and so reduce weight and downstream costs.

Many investment castings produced for the automotive industry go into high-loaded and safety-critical applications where defects could have serious and costly consequences. To address this risk, Impro employs both QA and QC tools and techniques to drive down the probability of defects occurring, and to find them should they arise.

If you need an IATF 16949-certified source for high quality investment cast parts, we can help. Contact us to arrange a discussion.