February 2022 Volume 4

OPERATIONS & MANAGEMENT

Tips for Effective Closed Die Forging Cost and Estimations By Bill Scott

Have you ever missed a process or a cost driver when working up an estimation for a raw steel forging? In this article we will cover in detail how to accurately and effectively estimate a steel closed die forging that will provide the ultimate desired outcome. This information is based on years of experience in the forging industry. The topics we will review are as follows, but not limited to: 1. Designing an accurate-effective forging. 2. Covering all estimating data points.

best way to obtain accurate steel weights, as you can set parameters within the software such as steel density, required flash thickness, etc. You may want to consider 3D modeling if you don’t currently utilize the software, as time is money in the estimating arena - it is much faster to create designs. Cover Essential Estimating Data Once you have the forging print proposal worked up, you are now ready to gather data and write up the estimate. I’m sure your business has guidelines established that are followed when writing up estimates, but things change often in the steel and forging industries. The following are keys to research when working on forging estimates. Determine the process. Know your weights at room temperature! • Is this a simple round or a complex non-round part? • Is this an upset forging or will you make it with the billet laying down? • If upset, establish the most effective upset ratio to avoid buckling issues. 2:1 is optimal if the billet fits in my experience. • What is the optimal stock size? • Is this round bar or round corner square, (RCS)? • Confirm the net weight of the forging after flash and punch out removal or final geometry. • Establish the cut weight required to make the forging. • Review weight percentage for expected scrap loss, (Kerf if sawed, Crop Ends if sheared). • Determine press size and furnace capacity. • Establish production rate. • Setup hours or multiple setups. • Include overhead and labor rates in the estimate. • Tooling cost and lead-time. • Factor in die life. RawMaterial Requirements Next, let’s review raw material requirements and touch on surcharges. Scrap is another key part of estimating a forging. As noted previously, a factor for human error should be reviewed and included based on forging complexity and part family history. As an example, a normal round forging yields from 1% to 3% scrap as a manual operation. Surcharges are also critical whereby the

3. Press size, furnace capacity and production rates. 4. Rawmaterial requirements and specifications. 5. Quality and shipping requirements.

Designing an Optimized Accurate Effective Forging Estimating a forging can be a tedious task depending on the complexity of the part and what it will take to meet customer requirements within your company’s capabilities. There is quite a bit of information that needs to be gathered in order to submit the best forging estimate. A forging design proposal is the first step in the estimating process. This must be within the forging company’s capabilities to produce the required geometry for the customer. Review the print thoroughly to determine if you can make the part or not. Don’t be discouraged if you feel you can’t make the part. It’s okay to no-quote. After all, it’s better to turn down a job than to take a chance where there are problems that cost your business revenue rather than making a profit in the end. If you are not 100% sure, ask those in the business who may have advice or can point you to someone who can make a determination. If the forging is within your capabilities, move on with the design if the EAU (Estimated Annual Volume), is favorable. Some customers supply their own forging print and that’s the way they want the part supplied. This makes it easier to work up the steel weight required to make the part. My preference has always been to ask for a finish machine drawing and do an overlay to make sure there is enough machine stock and tolerance to cover the equipment capabilities. Customers typically look for a minimum stock condition of 1.5mm after the forging tolerance is applied. Establish your design intent and know the press size you will be quoting on followed by adding machine stock and tolerance based on the intent. Keep in mind some surfaces may be as forged with surface condition requirements, which will affect the forging weights. There are formulas and 2D drawings to calculate steel weights and press tonnage, which is the way it has been done since industrial forging was established. It’s my opinion that 3D modeling is the

FIA MAGAZINE | FEBRUARY 2022 54