If you have a process that isn’t meeting specifications, using Monte Carlo simulation and optimization can help. Companion by Minitab offers a powerful, easy-to-use tool for Monte Carlo simulation and optimization, and in this blog we'll look at the case of product engineers involved in steel production for automobile parts, and how they could use Companion to improve a process.
The tensile strength of Superlative Auto Parts’ new steel parts needs to be at least 600 MPa. The important inputs for this manufacturing process are the melting temperature of the steel and the amount of carbon, manganese, cobalt, and phosphorus it contains. The following transfer equation models the steel’s tensile strength:
Strength = -1434 + 1.1101*MeltTemp + 1495*Carbon + 174.3*Manganese - 7585*Cobalt - 3023*Phosphorus
Building your process model
To assess the process capability, you can enter information about your current process inputs into Companion’s straightforward interface.
Suppose that while you know most of your inputs follow a normal distribution, you’re not sure about the distribution of melting temperature. As long as you have data about the process, you can just select the appropriate column in your data sheet and Companion will recommend the appropriate distribution for you. (If you like to try this yourself, here's the tensile strength data set).
In this case, Companion recommends the Weibull distribution as the best fit and then automatically enters the "MeltTemp" distribution information into the interface.
Once you have entered all of your input settings, your transfer equation, and the lower specification limit, Companion completes 50,000 simulations for the steel production.
Understanding your results
The process performance measurement (Cpk) for your process is 0.417, far short of the minimum standard of 1.33. Companion also indicates that under current conditions, 14 percent of your parts won’t meet the minimum specification.
Finding optimal input settings
The Companion Monte Carlo tool’s smart workflow guides you to the next step for improving your process: optimizing your inputs.
You set the goal—maximizing the tensile strength—and enter the high and low values for your inputs. Companion does the rest.
Simulating the new process
After finding the optimal input settings in the ranges you specified, Companion presents the simulated results for the recommended process changes.
The simulation indicates that the optimal settings identified by Companion will virtually eliminate out-of-spec product from your process, with a Cpk of 1.56—a vast improvement that exceeds the 1.33 Cpk standard. Thanks to you, Superlative Auto Parts’ steel products won’t be hitting any bumps in the road.
Getting great results
Figuring out how to improve a process is easier when you have the right tool to do it. With Monte Carlo simulation to assess process capability and Parameter Optimization to identify optimal settings, Companion can help you get there. And with Sensitivity Analysis to pinpoint exactly where to reduce variation, you can further improve your process and get the product results you need.
To try the Monte Carlo simulation tool, as well as Companion's more than 100 other tools for executing and reporting quality projects, learn more and get the free 30-day trial version for you and your team at companionbyminitab,com.