Desktop version

Home arrow Health arrow Case Studies in Maintenance and Reliability: A Wealth of Best Practices

Source

The Challenge

In a planning meeting in February, the Production General Manager (GM) who was chairing it wanted a plan to complete the installation of the machine tools in the new extension within 30 days. At the current rate of relocations, the activity would take over six months; he declared this to be unacceptable. The dust level over a prolonged period was likely to cause quality problems.

Furthermore, the inability to run the new lines at one site would result in unnecessary parts' movement, resulting in production scheduling problems.

Most of the people at the meeting were taken aback by this demand. The production process planning engineer and my mechanical department head said that raising the tempo from 3 to 17 machines a day appeared impractical. We had three low-slung trolleys and it was not possible to get 12 additional trolleys by August. The time available to train people to do the work was inadequate.

I sought time to study the issues involved before taking a stance.

Analysis

About this time, a young engineer joined my team as an intern for a year. He seemed an intelligent and enthusiastic person, so I assigned him to do the analysis. He knew nothing at all about Method Study, which was the process I wanted to use. We discussed the project and drafted a plan of action. The first job was to train him. As a student, I had myself used a good book entitled Introduction to Work Study published by The International Labour Office (ILO) in Geneva[1]. I gave him my copy and asked him to read the chapter on Method Study dealing with Flow Process Charts and String Diagrams. We spent an hour every day discussing his queries and after three days he was ready to start.

He spent a week following the work crew from the time that machines were disconnected to the time they were restarted. He charted the process carefully, noting the time for each activity. All the machine movements were recorded, so at the end of the week we had 16 charts (see Appendix 22-A for an explanation of process flow charts and string diagrams). During the next week, he recorded people-movements, using string diagrams. By the end of the second week, he had identified many weak spots in the current system. He reported that if we were able to make the necessary changes to the current process, the existing crews could move 5-6 machines per day. That was good, but not good enough.

Next he studied the string diagrams and looked for improvements (see Figure 22.4). One work practice caused significant delays, adding 40-60 minutes to the cycle time. This delay was the result of the plumbers and electricians walking to their workshops to fabricate the pipes and conduits. His plan was to move the light-weight pipe threading and bending machines to within 50-100 feet of the new location of the machines. This was acceptable, as long as dust levels were controlled. Reducing cycle time meant that 7-8 machines could be moved per day. This was progress, but still not good enough.

Our first impulse was to consider doubling the resources. We resisted that knee-jerk reaction, and decided to analyze the bottleneck resources and their effective working time.

String diagram of present method

Figure 22.4 String diagram of present method

the first and the last people to work on any machine.

  • 2. Company electricians worked 2 hours overtime per day for machine shifting activities.
  • 3. The contractors took about 2-3 hours per machine to measure, fabricate, and install the conduits and cabling.
  • 4. Each trolley was in use for 2-4 hours per machine movement.
  • 5. The 3 plumbers were busy for about 4 hours per day.

The main players in the team, including the production process planning engineer, met with the intern to review these findings and hear his proposals. He suggested the following actions.

a. We should schedule the work in two shifts of 8 hours each in place of the current 8-hour day work.

b. We start work with one electrician arriving 30 minutes before the rest, so that machines could be worked on as soon as the other crew members came in to work. The second shift electrician worked an extra 30 minutes at the end of the shift to reconnect and energize the last machine that was ready.

c. We would electrically isolate and disconnect 3 machines every 11/2 hours and prepare them for shifting.

d. The machine operators along with their tools, parts, etc., would move with the machines. They would help with the cutting oil refilling and in arranging the tool cabinets, etc., at the new location.

e. We would temporarily locate the conduit and pipe fabrication machinery and tools in the new building extension, between 50 and 100 feet of the machine tools being installed.

f. We would increase the contract crew size by two electricians, two plumbers, and four additional workers in the machine shifting crew. With these resources, we could form two shifts.

While there were doubts expressed with these proposals, especially about the resources and lack of additional trolleys, the participants agreed it was worth a trial. The only change was that we decided to order one additional trolley for delivery by end of July. We agreed to test out the new scheme during normal day shift movements in the existing buildings. This would help us evaluate the risks involved in attempting a step change in the rate of machine movements.

  • [1] The company electricians isolated the machines before anybody worked on them. Similarly, the company electricians waited for all otherwork to be completed before reconnecting the machine. They were thus
 
Source
Found a mistake? Please highlight the word and press Shift + Enter  
< Prev   CONTENTS   Next >

Related topics