Three product cost reduction tips for design engineers

“We have to launch a new variant in next 1 year and sales team has set us a target of 10% less cost than competition and ensure that there is performance improvement” this is a pretty common statement we hear in NPD briefing meetings. Because of either competitive nature of the business or as customer pressure, it is not new that that product cost reduction is one of the most discussed initiative in the organization. Traditional way cost reduction used to mostly hover around manufacturing cost reduction at plant or at shop level, where more focus of cost reduction is to improve the existing manufacturing process.

With advent of smarter 3D CAD platforms and being able to simulate the downstream processes earlier in design the focus has shifted towards looking at upstream cost reduction. VAVE (Value analysis and value engineering), Process six sigma, QFD, SPC etc various data analysis and methodologies for process improvement have proven extremely useful for driving Lean methodology for manufacturing and operations.

However organizations now realized that since 70% cost is locked in the design phase, whatever quick benefits that can be derived in manufacturing, that has already be done and there is not much impact now as it’s going to impact only 30% of the cost. The major chunk of the cost gets locked at design stage simply because type of manufacturing process driven by functional requirements and geometry of parts is decided with holistic approach. So simply the fate of the part is pretty much decided right when detailed design is created. Hence there is more seriousness towards initiatives like design to cost, early cost estimation or cost or design teams. It has become more like differentiation for innovative organizations to succeed in the market.

Hence, it is crucial for design engineers to keep focus on few simple but vital areas of design which would help in driving the cost reduction.

Material cost is key for high volume additive processes

Hence, it is prudent that tooling cost and process can be overlooked for very high volume of production as material contributes most in such scenarios.

However, for subtractive processes it could be different. For Milling, turning operations, where material gets removed mostly, if a part is made from standard billets or bars, and if the material is standard MS or SS, then material cost would be something that need not be worried about. As more important would be to look at process cost. However material cost of Titanium or such precious material could be Hugh even for per mm of material added to a part.

Avoid over processing of mill and turn parts

Buy to fly ratio often used term in aerospace industry is one of the greatest indicators of over processing. It simply takes into consideration of raw material used before manufacturing and how much is left after manufacturing. This is important as every chip of the metal that get is removed in machining needs dollars to be spent to achieve the final shape.

For harder material, the material removal rate (MRR) could be even low and that means it is going to take longer milling cycles to crate the final geometry. Near net shape (NNS) hence is the common term used in manufacturing to ensure the shape of material should be circular or rectangular (square) to reduce the cost. This ensures that at time very low material needs to be processed and thus the cost of process goes down.

Also, it is important to note what material is getting processed. For a hole of simple 10 mm diameter and 20 mm depths in SS may take few seconds but for Titanium it may take minutes! There are materials which are difficult to processes. Materials which deform very easily because of heat are equally difficult to process. Aluminum is one of such engineering materials apart from gold, silver, and lead.

Generally, machinability index for materials can help in defining machinability and thus leads to early identification of such materials which are hard to process.