Case Study #3
You are working as a quality improvement engineer at a firm (ABC) that produces plastic gears for small
motors, such as those in hand tools and appliances (e.g., electric screwdrivers and blenders). The primary
customer for the gears is ACME Manufacturing. Recently, ACME has been complaining to your sales staff
of late delivery of trucks containing ABC gears.
ACME has monitored and examined their production process by recording truck delivery time, as shown
in the table below. In the past, ACME states that trucks were rarely exceeding eight (8) days for delivery.
Truck # Delivery Time Truck # Delivery Time Truck # Delivery Time
1 5 14 5 27 8
2 10 15 8 28 7
3 6 16 8 29 9
4 6 17 9 30 7
5 7 18 7 31 10
6 8 19 9 32 8
7 7 20 6 33 7
8 8 21 10 34 7
9 9 22 5 35 8
10 5 23 6
11 9 24 7
12 6 25 8
13 6 26 6
1. ACME wants to show the variation in delivery time. Select and plot the delivery time data on the
most appropriate quality management tool. (Hint: consider classes of delivery days, such as 0-3,
4-6, 7-9, etc.)
2. Does ACME have a valid compliant? (You will need to report the percentage of late deliveries.)
ACME continues to complain to your sales team about late deliveries. As any good quality engineer, you
have already begun to investigate potential causes of late deliveries. Your team has collected some
significant data as shown in the table below.
Cause Code Frequency
ABC production delays A 20
Trucks not available for loading B 10
Truck breakdown in transit C 190
Employee absenteeism D 12
Low-skilled workers E 30
Loading forklift out of service F 110
Incorrect packaging material G 15
1. Choose an appropriate quality management problem-solving tools to identify the root cause of
the late deliveries. You must show a visual solution and provide a description of the root cause
of late deliveries for full credit.
2. Using the data provided, construct the most appropriate quality problem-solving tool to identify
which variable(s) have the most influence on the ability of ABC to provide gears to ACME.
You have directed your team to further investigate delivery times from ABC to ACME. One of your team
members suspects a potential relationship between order quantities and delivery time. The following
table shows the number of boxes of gears ordered and actual delivery time in days.
Quantity 5 10 15 20 25 30 35
Delivery Time (days) 7 3 10 5 4 8 6
1. Use the data in the table to select and construct the most appropriate problem-solving quality
method to check if there is a relationship between order quantities and delivery time.
2. Describe the next steps for ABC based on your results and analysis of quantity vs. delivery time.
Case Study #3 Enrichment
All the gears manufactured by ABC require a set of ball-bearings. ABC outsources the ball-bearings from
XYZ Company. While ACME is ABC’s largest customer, ABC has many other customers and manufactures
hundreds of thousands of gears and other plastic parts per month. ABC has committed to Lean Production
to save cost and is introducing Kanban to reduce inventory.
Using the data in the table below, how many Kanbans are required?
Daily Demand 2000 ball-bearings
Lead Time 4 days
Safety Stock 1 day
Kanban Size 1000 ball-bearings