Johnston Products Case Study: Master Scheduling & Production Issues

This case study focuses on the production scheduling challenges faced by Johnston Products, specifically the issues of "front-loading" the production schedule, leading to significant delays and inefficiencies. Justin Wang, the master scheduler, struggles with supervisors attempting to catch up on previous week's production shortfalls, causing the master schedule to be reconstructed frequently. The case examines several potential contributing factors, including outdated job standards, the emphasis on high utilization, high workforce turnover, and frequent engineering changes to the product designs. The assignment requires calculating the standard time required for production based on provided data, identifying the root causes of the problems, and developing a comprehensive plan to regain control of the production schedule under the existing constraints of the company. The analysis includes evaluating the impact of each factor and proposing strategies to improve scheduling accuracy, reduce delays, and enhance overall operational efficiency.

CASE STYDY 6.1 Johnston Products
No matter how many times Justin Wang, the master scheduler for Johnston Products, tried, he
couldn’t seem to get it through people’s minds. They kept trying to “front load” the production
schedule, and the problem appeared to be getting worse.
By “front loading” Justin meant that production supervisors would attempt to catch up with
production they failed to make the previous week. It seemed to happen every week, and the only
way Justin could get things back to a realistic position was to completely reconstruct the entire
master schedule—usually about every three weeks.
Last month could serve as an example. The first week of the month Justin had scheduled
production equal to 320 standard hours in the assembly area. The assembly area managed to
complete only 291 hours that week because of some equipment maintenance and a few
unexpected part shortages. The assembly supervisor then had the workers complete the
remaining 29 hours from week 1 at the start of week 2. Since week 2 already had 330 standard
hours scheduled, the additional 29 hours really put them in a position of attempting to complete
359 hours. The workers actually completed 302 hours in week 2, leaving 57 hours to front load
into week 3, and so forth. Usually by the time Justin came to his three-week review of the master
schedule, it was not uncommon for the assembly area to be more than 100 standard hours behind
schedule.
Clearly, something needed to be done. Justin decided to review some of the areas that could be
causing the problem:
1. Job standards Although it had been at least four years since any job standards had been
reviewed or changed, Jason felt the standards could not be the problem—quite the
opposite. His operations course had taught him about the concept of the learning curve,
implying that if anything the standard times for the jobs should be too high, allowing the
average worker to complete even more production per hour than that implied by the job
standard.
2. Utilization The general manager was very insistent on high utilization of the area. He felt
that it would help control costs, and consequently used utilization as a major performance
measure for the assembly area. The problem was that customer service was also
extremely important. With the problems, Justin was having with the master schedule, it
was difficult to promise order delivery accurately, and equally difficult to deliver the
product on time once the order promise was made.
3. The workers In an effort to control costs, the hourly wage for the workers was not very
high. This caused a turnover in the workforce of almost 70% per year. In spite of this, the
facility was located in an area where replacement workers were fairly easy to hire. They
were assigned to the production area after they had a minimum of one week’s worth of
training on the equipment. In the meantime, the company filled vacant positions with
temporary workers brought in by a local temporary employment service.
4. Engineering changes The design of virtually all the products was changing, with the
average product changing with respect to some aspect of the design about every two

months. Usually this resulted in an improvement to the products, however, so Justin
quickly dismissed the changes as a problem. There were also some engineering changes
on the equipment, but in general little in the way of process change had been made. The
setup time for a batch of a specific design had remained at about 15 minutes. That forced
a batch size of about from 50 to 300 units, depending on the design. The equipment was
getting rather old, however, forcing regular maintenance as well as causing an occasional
breakdown. Each piece of equipment generally required about three hours of maintenance
per week.
Since the computer had done most of his calculations in the past, Justin decided to check to see if
the computer was the source of the problem. He gathered information to conduct a manual
calculation on a week when there were eight people assigned to the assembly area (one person
for each of eight machines) for one shift per day. With no overtime, that would allow 320 hours
of production.
Product Batch Size Standard Assembly Time (minutes per item)
A174 50 17
G820 100 9
H221 50 19.5
B327 200 11.7
C803 100 21.2
P932 300 14.1
F732 200 15.8
J513 150 17.3
L683 150 12.8
Case Analysis
1. With this information, Justin calculated the total standard time required to be within the
320 hours available. Is he correct? Calculate the time required and check the accuracy of
his calculation.
2. List the areas you think are causing trouble in this facility.
3. Develop a plan to deal with the situation and try to get the production schedule back
under control under the constraints listed.
(Arnold 145-146)
Arnold, J. R. T., Stephen Chapman, Lloyd Clive. Introduction to Materials Management, 7th
Edition. Pearson Learning Solutions, 10/2016. VitalBook file.
The citation provided is a guideline. Please check each citation for accuracy before use.