Leading cost estimating methods for machining

Manufacturing firms need to have an accurate estimate of product design and development costs. This is especially important these days because the shorter lifespan of products accentuates the importance of design and development stages. There are two main cost estimation algorithms: feature-based cost estimation and parametric cost estimation.

Feature-Based Cost Estimation

The estimation algorithm that most closely follows the machining processes used to manufacture a part will be feature-based cost estimation. Manufacturing cost is determined by shape complexity, product precision and tooling process.

If these requirements can be obtained and considered during the design stage, estimating manufacturing cost during the early product development stage should become a reasonable task. Feature-based cost models use bottoms-up estimating principles and formulas (speeds and feeds, machine cut/bend rates, etc.) to generate cycle times, so estimating is not only much faster than traditional methods but extremely accurate.

The ultimate feature-based cost estimation would be to actually do the CAM work for the part, generate the code, run it through a simulator, and base estimates on that information. Unfortunately, that is generally too complicated. An experienced machinist can look at a print for a part, or even a simple sketch, and pretty quickly decide on a set of machining operations that will produce the part.

Or you could use feature recognition software to analyze a CAD model and output a set of features. And once the set of features needed to manufacture a particular part is determined, you can fill details in until you have a full-fledged feature-based cost estimate.

Parametric Cost Estimation

However, suppose the part you’re trying to estimate is similar to a lot of other parts you’ve estimated in the past. Perhaps you are a socket manufacturer and you have detailed knowledge about the cost to manufacture sockets on hand.

The idea behind parametric cost estimation is to create a model that allows you to tell it the overall specifications, or parameters, for one of these parts; and it will use the accumulated data to produce an estimate. Parametric cost estimation works well provided the type of part you’re estimating is nominally standard and you have data on hand for what it will cost to build.

There are cost estimation vendors that have such databases as well; but the difficulty is in knowing how consistent their database is and whether it matches costs closely enough to be useful. Unfortunately, the only way to tell this is to buy the cost estimation software and use it for a while, which is an expensive way to find out.

Today, parametric estimating is usually applied to large systems, such as those performed for the Department of Defense. While many parametric analysts use commercially available general-purpose cost models, many others have created their own models to satisfy specialized needs. Your level of expertise and experience will dictate your choices in this crucial area.

Cost estimating, however you apply it, is a crucial part of the manufacturing process. When combined with a machining partner that can match your needs, it will help in many aspects of the process

If you want to learn more about how Arnold Machine can be that machining partner, read more about us.