Using Design Reviews
You have now made the decision that the product you are currently designing will need to use castings. You contact your chosen foundry and begin discussing enlisting their assistance. The drawing you send to your casting supplier contains lots of vital information about the casting you want to produce, such as material type, dimensions and tolerances, and datum targets. However, these are not the only items of importance that the casting supplier should be made aware of. To properly relay all the critical information at this point in the project, you should consider holding design reviews with the foundry team. A design review is an opportunity to get all the stakeholders together to review all aspects of the casting and not limit the discussion to only the design.
So, who are the stakeholders in a design review? As a best practice, any department or team that will have contact with the casting should have a representative at this meeting. From the OEM side, representatives from purchasing, supply chain/logistics, manufacturing and engineering are commonly included. From the foundry side, teams from casting engineering, manufacturing, shipping, and the patternmaker are invited.
When I first started working in the foundry industry, these reviews were often called “kickoff meetings,” and were held after the tooling and sample purchase orders were released to the foundry. We reviewed dimensions and tolerances, material, and metallurgy topics, and these meetings were basically a one-way discussion with the casting customer telling the foundry what was needed. Over time there have been positive changes made, and now design reviews are held much earlier in the design process to facilitate open discussions from the foundry perspective on improvements that could be made to improve the castability of the part before the design itself was finalized. This two-way dialog is a significant improvement over what was done previously by allowing changes to be made not only to the physical design features of the casting but to the manufacturing process as well.
What topics should be discussed during these meetings? At this point in the design of the casting and the process, no questions should be off the table. This is the power of getting all the parties involved with the casting together; everyone will have a slightly different view on what they consider important, so now is the time to bring these thoughts out.
For example, the OEM engineer should review the operating environment of the finished casting with the foundry team. What is the function of the casting? Where is it used? What type of environment (hot, cold, caustic, etc.) will the casting be subjected to? Is the casting visible in the finished state or is it deep within an assembly? What surface finish and cosmetic requirements are there? Will this casting be serviceable by the end customer? What are the warranty expectations from the viewpoints of both parties?
Items from the foundry perspective may include such things as what type of finish, such as paint or plating will be applied to the casting. Will paint masking of machined surfaces be required? Can the casting be redesigned to eliminate the need for cores? Can the parting plane be flat, which could reduce the complexity of the pattern equipment? Does solidification modeling show any potential areas where defects such as shrink may occur? Are wall thicknesses and the location of heavy cast sections conducive to the gating and risering scheme? Can any potential machining operations be reduced or eliminated by effectively using the casting process?
Packaging is often an item that is overlooked during the design phase, so be sure to include this topic in your discussions. Will special packaging be required? How should the casting be oriented in its shipping container? Will rust preventative be required? Will castings need to be wrapped or separated in some manner to avoid damage during shipment?
Design reviews are powerful tools that can accelerate the design process of both the casting and the manufacturing processes used to produce the final part. To be their most efficient, they should be held as early in the design process as possible and should be repeated at set intervals leading up to the release of the final casting design. If you aren’t using these today, set the wheels in motion to start them on your upcoming project; you’ll be impressed with the results.
Click here to view the column in the May/June Casting Source Digital Edition.