Customised pass-through oven solves heat-treating challenge

Dimensions and temperature uniformity specifications of the oven posed a major technical challenge

The Carbolite engineering team designed and built a custom loading system

Carbolite, the UK’s largest manufacturer of standard laboratory and bespoke industrial ovens, has helped to create a customised manufacturing solution for a leading producer of arterial stents used by clinicians to treat cardiovascular disease.

The stent manufacturer was looking for a customised design to meet its precise production requirements and approached Carbolite to create a class 10,000 clean room oven solution.

Although the stents require heat-treating only to a maximum of 400°C, the dimensions and temperature uniformity specifications of the oven posed a major technical challenge. The solution calls for a chamber nearly 1.5 metres deep to be heated with a stability of better than ±1°C under steady state conditions coupled with temperature uniformity better than ±5°C.

To ensure good temperature uniformity the oven is divided into three separately controlled zones. The main program controller is digitally linked to two slave controllers that automatically track the program set in the main controller.

A digital time temperature program controller manages the temperature of the oven and is capable of storing up to 20 programs each with up to 16 segments. A program segment relay is fitted that can be set to sound an audible alarm at the end of the pro-gram. The oven employs forced air circulation carefully positioned to give optimum uniformity of the zones.

A specially designed load management system is also a key requirement because the stent manufacturer needs to load the untreated arterial stents quickly and easily into the chamber through the ‘front door and unload the medical devices through the opposite door within a cleanroom environment.

Carbolite’s engineering team designed and built a custom loading system that allows the stents to be loaded onto mandrels that could easily be transported straight from a carrier on a trolley into the oven chamber ready for the heat treatment process. The loading system features an adjustable support frame that holds 30 shafts up to 10mm diameter and 1400mm in length.

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