purchasing points P
Defect Analysis—What Is Your Role? Bob Mueller Jr., Joy Global Surface Mining, Milwaukee
of communication between all critical areas of your metalcaster’s operation can be the step that makes the partner- ship world-class. In today’s metalcasting environment,
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on-time delivery and overall quality are the elements of survival. T is fact requires an accurate, quick response to quality issues you may face within your own operation. Rejected castings not only cause immediate delays with lost produc- tion; the time required to return a part to your metal casting supplier, coupled with the time it takes your supplier to analyze the problem, correct it and send you replacement parts, is wasted time you can help minimize. Proper defect iden-
ommunication between you and your metalcaster is the key to a long, pro- ductive relationship. Ef- forts to expand that line
team requires additional experience and exposure to the problems. Your metal casting suppliers will
welcome the opportunity to help provide a full educational experience in defect analysis and the root causes behind them. T is process would require you to spend time in your met- alcaster’s facility, but the eff ort to gain knowledge in the metalcasting process will be well worth it. Work with your primary metal casting suppliers to ar- range a schedule and agenda that will give you a basic set of tools to practice your defect analysis skills. T is training
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tifi cation at the time of occurrence can help provide your met- alcaster with valuable information before the long process of return- ing product takes place. Its ability to react to this information can minimize delay and get conforming material back in your shop. So, how do you become an asset to your supplier and provide accurate information on metal casting defects you might know nothing about? In your metal casting design or pro-
curement career, you likely have seen the majority of defects typically found in metal castings many times, and have heard them identifi ed under many clas- sifi cations, trade names and industry labels such as “dirt” and “crud.” T is experience is a good basis to start with, but accurately breaking these defects down and providing a clear direction to your supplier’s quality or engineering
cast product line. T e process tracks individual part numbers, classifi es defects and maps them on either prints or solid models. It is relatively new, but already it has proven useful in identify- ing trends on certain metal castings. For example, I was consistently
Another tool I use in conjunction with identifi cation and classifi cation of metal casting defects is to track and map out defects to look for consistency and trends.”
should cover multiple sessions with your supplier to build your knowledge base and methods for communicat- ing with the metalcaster. Over time, your confi dence will grow as will the confi dence your metalcaster will have in your analysis. Regardless of the level you choose to take this educational experience to, the knowledge in defect analysis and the metalcasting process will prove very valuable. Another tool I use in conjunction with identifi cation and classifi cation of metal casting defects is to track and map out defects to look for consistency and trends. T is project was started by an engineer at one of my largest steel casters, and I utilized it for my entire
fi nding a linear defect on a steel cast- ing that had, for years, been classifi ed simply as a crack. In my informa- tion gathering phase and subsequent mapping of the defect, I found it was consistently just outside an isolated heavy section of the part. Further investigation and testing discovered an area of microshrink- age that was uncovered after signifi cant material was removed during a combination of pre- and fi nal machining. T e metalcaster in this case was able to address the area with additional feed- ing, and the problem has been eliminated. T is part was one of the leading causes of rejections in my machine shop. T e relationship
between the OEM and the metalcaster is one that should be viewed as a partnership. In this
way, you have the ability to aff ect the relationship in a positive way for the benefi t of both companies. Defec- tive metal castings always will have a negative impact on both you and your metalcaster. With your help, these im- pacts can be minimized and, in some cases, eliminated altogether. Reach out to your metal casting suppliers and ask to be part of the solution through edu- cation in both the metalcasting process and proper defect analysis. Your eff orts in this way are sure to yield positive results for all involved.
Bob Mueller Jr. is senior supplier quality engineer, cast product and casting supplier development, for Joy Global Surface Mining, Milwaukee. He has more than 30 years of casting experience.
Nov/Dec 2014 | METAL CASTING DESIGN & PURCHASING | 49
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