Troubleshooting Ceramic Process Problems and Links
It important to be in control of your process and understand it to troubleshoot problems well. If not you will not know how to ask the right questions that will bring the needed answers. Production problems are often blamed on the materials so we attempt to examine this in this area of the database. There is no question that machines, kilns and the people who operate them are responsible for alot of production issues but that will be dealt with to a limited extent here.
Admittedly if materials are not consistent then variation in them will definitely be a cause of many problems. But if you think the materials are different is it because you are testing the properties critical to your process and have numbers to prove it? If you depend on consistent materials can you afford not to be testing? If the materials are consistent then you must learn to adapt your equipment and people to them and to articulate what properties need to be adjusted and how. It is interesting that many factories around the world employ materials that others might think would be impossible to use, but their secret is adaptation, knowledge and experience. Early in the planning stages of any production project there should be an assessment of the available materials, especially what their strengths and weaknesses, are so that a production line can be adapted accordingly or these materials can be blended with imported ones to move properties in the needed direction.
It is important also to appreciate, of course, that different types of product produced using the same process and equipment present varying challenges. However the level of difficulty is often under estimated. For example, if you produce plates of diameter x and want to produce larger ones, the amount of cracking and warping problems will increase at a dramatically higher rate than the size. Plates that are 25% larger might have 100% more problems using the same process. Likewise, if you are not testing the firing response of your body at temperatures that are higher and lower than your production temperature you might not be aware of how volatile its color response is, for example, when overfired. Likewise problems like warping, bloating, cracking can be lurking just beyond the boundaries of your process and small changes in materials or process could bring dramatic increases in reject rates.
It is possible that you have operated for many years making a specific product using the same production machines and the same procedures and materials. Such situations can breed complacency and routine testing may be discontinued (and even technical staff dismissed or not replaced). Many plants have also become increasingly dependent on consultants and technical support from suppliers. While these have a place, you need to be watch day-to-day and be able to react quickly to production problems. The secret is being able to ask the right questions to find the cause (or more likely the causes). If you are having many problems chances are you are not doing routine testing. For each of the problems in this area we have provided links to tests you can do to avoid these problems in future.
By Tony Hansen
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- Kaolin - Al2O3.2SiO2 or Al2Si2O5(OH)4 - Hydrated alumina silicate, Pure clay mineral