A new approach to monitoring process temperatures during sintering
Feature article: PIM International, Vol.5 No.1 March 2011, pages 55-57, 1340 words
The Edward Orton Jr. Ceramic Foundation, 6991 Old 3C Highway, Westerville, Ohio 43082, USA
A new system developed by the Orton Ceramic Foundation, based in Westerville, Ohio, USA, offers PIM parts producers the chance to routinely record the performance of their sintering furnaces, including peak temperature and time at temperature.
Such a system has been designed to supplement the use of existing thermocouples and routine temperature surveys, but with the added benefit of providing batch-to-batch data records that can be logged for improved process monitoring.
Sintering is a critical step in the production process of powder injection moulded components. Sintering furnaces benefit from Temperature Uniformity Survey’s (TUS’s) to meet the requirements of quality control/assurance procedures, however there is the “dark side of the moon” period between surveys in which there is the possibility of unwanted surprises from the sintering process.
If you passed your last survey, but you fail your next survey, how do you know when something changed in your sintering process? Was it two days before your bad survey or was it two days after your good survey?
Based on proven materials technology the Orton Ceramic Foundation, based in Westerville, Ohio, USA, has developed an easy to use tablet shaped product, called TempTAB, that allows users to monitor and document their thermal processes as frequently as they believe necessary.
The product can be used in both batch and continuous furnaces and is designed to work in most atmospheres including air, inert or reducing atmospheres. TempTAB’s have been processed to remove any organic binders used in the forming process so there is no out gassing of any organic material and they are able to survive rapid heating and cooling cycles.
The tablets are made from blends of inorganic materials that are selected based on their predictable shrinkage when exposed to elevated temperatures. The small disc shaped tablets (28 mm x 7 mm) have a flat index surface and a hole in the centre (Fig. 1).
The tablets have been designed to be sensitive to both maximum temperature and time at temperature, the combined effect of time and temperature is often referred to as “heat work”. The real proof of TempTAB sensitivity is the correlation between the readings provided by the TempTAB and the physical properties of the product being sintered.…..….
Further sections of this paper include:
- Case study
- Using TempTAB
Figures and Tables:
Fig. 1 TempTABs before entering the furnace
Fig. 2 The etched, 800x images reveal the degree of sintering at 2,050°F for times of 5, 10, 20 & 30 minutes (Courtesy of Powder-Tech, Inc.)
Fig. 3 TempTABs entering sintering furnace with minimal disruption to production
Fig. 4 TempTABs exiting a sintering furnace
Fig. 5 TempTAB is measured after exiting the furnace and the dimension is entered into the software.
Fig. 6 TempTAB Trakker Software automatically transforms the dimensions into process temperatures and provides the data in both table and graph form for monitoring
Table 1 Constant temperature with varying hold times
Table 2 Constant hold time with varying temperatures
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