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Quality, Technical Checklist for a Prospective Foundry

Dave Charbauski

In the last issue, I reviewed discussion points regarding management issues to explore with a prospective foundry. To help you determine if the foundry has the potential to fulfill your needs, let’s cover the topics of foundry quality and technical capabilities. 

Let’s begin with the foundry’s quality metrics––how do they measure themselves and what are those numbers?Parts per million (PPM) is usually the most common quality metric in terms of rejected/returned material. What is their PPM and how does align with your targets?When it comes to internal rejections, most companies choose to state their rejections as a percentage of parts produced. Generally speaking, greensand foundries that run an internal scrap rate of less than 1% are doing well. You should review their current numbers and also go back a few years to get an overall idea of the trend in these metrics. 

Does the foundry hold a certification such as ISO or TS?If so, who is the registrar and what is the expiration date of the certification? When was their last audit? Do they perform internal audits of their processes?Do they have process sheets and work instructions, and can you look at an example?These questions will give you a better idea of how they manage their quality management system. 

Traceability is an important topic to discuss when reviewing a foundry’s quality capabilities. If you have ever been involved with an issue that required the containment of a batch of material produced at a certain time or from a particular heat of material, you already know the importance of keeping production records. Find out how detailed their records are. Recording date codes only tells you the day of production––do they have additional methods to identify what shift the parts were produced on, and perhaps what hour they were produced?Is the foundry capable of telling you not only when the casting was produced but also the heat number it was poured from and the chemistry of that particular heat? 

Proper gating and riser design is vital to the production of a conforming casting. What methods does the foundry use to develop the gating and risering systems?Do they use solidification modelling to develop a risering scheme that produces a sound casting?Do they use it on all castings or only on more complex or difficult-to-produce castings?Solidification modelling has become affordable for foundries and allows them to develop a proper gating and risering design before any tooling is produced. It should be used during the development of every casting the foundry produces. 

Another technical capability is the foundry’s ability to check and analyze their own parts and materials. Does the foundry have an in-house metallurgical lab and do they have a degreed metallurgist on their staff?A complete met lab should have a spectrometer for chemical analysis (along with a combustion type carbon and sulfur determinator for iron), polishing equipment and microscopes for microstructure analysis, and a tensile test machine. Along with testing metals, the foundry should also be capable of testing their sand––there should be a functioning sand lab that checks key sand characteristics daily. 

Dimensional inspection of castings and tooling should be performed in-house. Most foundries have a CMM for measurement. If the foundry is only using granite plates and height gauges or other hand tools to check a casting, they may be missing important characteristics. The ability to 3D scan a casting in-house is also becoming more desired by OEMs. 

On the topic of measuring tooling, does the foundry have a program in place to check their pattern equipment for excessive wear?Also, do they perform and document a pattern review to check for wear and damage before a pattern is released for a production run?Does the foundry have a pattern shop on site that builds new patterns or do they only perform maintenance and gating system changes? 

Finally, is the foundry willing to take on additional first tier responsibilities, such as sending parts for painting, heat treating, or machining done to the castings they produce before shipping them to you? 

Remember that the discussions you have with a prospective foundry are important. You aren’t trying to challenge their capabilities, but rather, have a better understand how they fit in with your needs. Once you have a good idea of what they have to offer, schedule a visit to their facility to experience their offerings first hand.