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September 15, 2014

Some Projects Require More Data Than Others

Filed under: Food for thought for friends,Professional Development — Alec @ 12:58 pm

Some projects just require a lot more data collection. One project that we completed in 2007 was that kind of commitment. We took a look at the manufacturing process for an orthopedic cutter. The process had been around for 10 years and had been subjected to numerous process improvement events. Strangely, all of the prior attempts at cost reduction and quality improvement had been focused on the 32 operations as singular processes rather than looking at the whole system of operations.

The original process included 32 operations to complete a high volume, high precision family of cutters. The total manufacturing cost was about $20. But, in order to keep the business from moving to Asia, a major cost reduction was necessary.

Our first step was to do a detailed Value Stream Map (VSM). However, with 32 operations we really needed to go look at each operation individually and collect lots of data. We analyzed more than the normal minutes per piece at each operation. We also explored:

• variable and fixed burden rates

• probable activity based burden rate

• set-up times for each machine

• quality

• rework

• the queue ahead of each operation

• man time

• steps between operations

When I speak about man time I am referring to the part of the total cycle time that requires a person to be present. For example, a Computer Numerical Control (CNC) mill only has a small amount of time to load, unload and gauge a part, but an Assembly Machine may take the total cycle time.

We observed how much waste handling there might be within an operation because it was not a cell. In other words, if we could eliminate the need to pick up in order to start the process and to pack in order to end each operation, we could save a little time. So, we looked at Takt time (the cycle time required to meet the customer demand). We compared the Takt time to the actual cycle times and identified all the operations that had a cycle time less than the Takt time. When the operation was significantly less than the Takt time, we examined the opportunity to do another operation within that machine (a second load – A & B position fixture).

Quality, rework and high set-up time operations were the most important target for 5S (the fundamental building blocks of an organization- sort, set, shine, standardize, and sustain) and Single Minute Exchange of Die (SMED), even before we could tackle Cellular. The quality side required we do a Design of Experiments (DOE) to determine the real process capability. Most processes have 10 to 20 factors that when varied have an impact on the results. Usually there are only a few that have significant impact over a small range. Often we know and can easily control which factors have an impact. However, there are times that a few significant factors that are not known may even be an interaction. By collecting data and doing a few DOE we can identify the significant factors that must be tightly controlled. With our DOE, a few significant factors were identified and the process was suddenly statistically capable. Some fixture standardization and magnetic chucks with the 5S reduced set-up times.

We posted a 3-foot by 4-foot spreadsheet on the wall so we could compare what operations might be combined due to Takt time capacity or Open Man capacity. Then, one by one, we put together our dream process and modified our spread sheet to see what impact these combined operations had on capacity, man cycle time, variable costs, walk distance, and set-up time.

Some of the most obvious things were how many redundant operations occurred such as wash. There were 4 wash operations in the original process when in reality a single rinse in a small pail of water was satisfactory for all but the final wash.

The original process had:

• 4 washers

• 32 operations

• 25 racks for WIP (Work in Progress)

• walk time more than the standard hours per part (or over 1000 steps)

• 18 of the operations took less than 60 seconds

 

The final streamlined process identified included:

• 2 small manufacturing cells with Heat Treat in between

• 2 washers

• 14 operations

• 6 racks including in and out for Heat Treat (40 steps per part)

This resulted in a 60% reduction in variable cost. Conclusion: Sometimes it takes a lot of data and multiple perspectives from lots of people to see the opportunity.

 

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