Vacuum heat treatment in the automotive industry

The heart of state-of-the-art transmission technology

A huge transformation is taking place in today’s automotive world. Electric cars, stricter emissions regulations and the desire for more efficient vehicles are driving the industry forward. However, one of the biggest challenges remains, the development and manufacturing of modern transmissions. This is where traditional engineering expertise meets the requirements of new, sustainable mobility. How Graphite Materials was able to help find a future-proof, sustainable solution.

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Background

A modern transmission must not only be powerful, but also lightweight. This becomes all the more difficult when you consider that cars today are often equipped with smaller but more powerful engines. The challenge is to build a transmission that brings this increased power to the road with as little energy loss as possible. The principle of “surface carburization” is used to ensure that gearbox workpieces are both hard and resistant and remain flexible. In this process, the surface of a steel component is hardened by the incorporation of carbon atoms. The core remains ductile, while the surface of the workpiece becomes harder and more wear-resistant.

Overview

Industry:

Automobile

Procedure:

Low-pressure carburizing with high-pressure gas quenching

Solution:

Individually designed CFC fixtures with optimized component nesting

Services:

Analyzes and FEM simulations, new design, production of CFC charging racks / batch carriers / workpiece carriers / CFC fixtures / CC fixtures

Result:

Significant improvement in the cases of the distortions

The challenge

Case hardening using low-pressure carburizing (LPC) with high-pressure gas quenching (HPGQ) technology was selected to produce a delicate, thin-walled ring component due to the high quality requirements (shape and dimensional tolerances, hardening parameters). The treatment was carried out in a modern vacuum heat treatment system

. During the carburizing process, the components are heated to temperatures of around 900°C in the oven. This allows the carbon to diffuse from the process gas into the component surface. The component is then cooled quickly to fix the diffused carbon atoms in the structure of the surface.

The following challenges are requested to be considered:

Quality: minimal distortion of components after treatment
Process reliability: reproducible and reliable results
Cost efficiency: optimization of manufacturing costs

The goal: hardening thin-walled metal rings

Ein dünnwandiger Ring wurde einlagig auf einen CFC

-Träger im Vakuum einsatzgehärtet. Die Bauteilpositionierung des verwendeten Chargiermittels war für die Serienproduktion nicht optimal. Dies führte zu einer inakzeptablen Abweichung der Rundlaufgenauigkeit. The component positioning of the charging agent used was not optimal for series production. This resulted in an unacceptable variation in concentricity.

Process results

By a comprehensive analysis of the existing process, we identified various possibilities for optimization.

Component-compatible carrier design

The positioning of the rings has been redesigned. In a series of tests, In a series of tests, 700 rings from four different batches were measured and evaluated after heat treatment on the optimized carrier. The shape and dimensional deviations were all within the required tolerances.

The result

According to the optimized fixture design, the maximum values of the roundness deviation were reduced by 25 % and the average deviation by 50 %.

Not a single ring had to be declared as a reject.

The new fixture design was approved for series production and implemented as a new standard.

Your contact person

Eduard Lassel

Head of Engineering

+49 911 999 01 03-40

eduard.lassel@graphite-materials.com