The document analyzes equipment availability for a bottling line that produces different bottle sizes and flavors. It summarizes existing analysis showing the filler machine's throughput and mean time between failures (MTBF). The goal is to improve throughput and reduce inventory costs. The document presents a new availability analysis using a general renewal process model to calculate MTBF over various run lengths. The results show longer runs have higher throughput and MTBF, allowing up to a 25% reduction in inventory levels for a 4-hour run if the filler's throughput is improved to 380 bottles per minute.

1. Equipment Availability Analysis
Fred Schenkelberg, Ops A La Carte,
LLC Angela Lo, Kaiser Permanente

2. Overview
• Bottling line
– Multiple bottle sizes
– Multiple flavors
• Build to finished goods inventory
– Mixed shipments of FG to distribution centers
– Daily shipments
– Broad variation in demand of bottle size and flavor

3. Introduction
• Throughput directly related to inventory size
• Inventory is expensive
• Goal is to improve the throughput to
equipment capabilities seen over long runs to
short runs.
How much inventory reduction is possible?

4. Existing Analysis
• The filler (bottleneck) has the following values
Given a 400 bottles / min equipment average capability

5. Desired Improvement
• (Anecdotally) the line runs better over time
• Improve the analysis to calculate MTBF over
various length runs
• Make the calculations time dependant

6. Mean Cumulative Function

7. Filler - Time to Failure

8. Filler - Time to Repair

9. General Renewal Process
• Assumptions
– Time to first failure is known (Weibull)
– Time to repair is negligible relative to runtime.
• Permit modeling of repairs that are between
– As good as new
– As bad as old

10. Cumulative Failure Intensity vs Time

11. New MTBF Values
Length of
run 120 240 480 960 1440
(minutes)
Cumulative
7.17 9.29 11.56 13.26 14.16
MTBF
Instantaneou
s 20.75 26.53 32.57 37.45 34.72
MTBF
The long term MTBF value is 45.6, resulting in approximate
2.63 minutes to build 1000 units. Building the same inventory
faster, permits the inventory reduction.

12. Results
Length of
run 120 240 480 960 1440
(minutes)
Time to build 3.53 3.33 3.19 3.12 3.09
1000 units
%Improveme
nt 25.5 20.9 17.5 15.6 14.7
with 380/min
For a 4 hour run (240 minutes) if the equipment is improved to
a 380/minute throughput, there is at least a
20% inventory reduction

13. Summary & Conclusion
• Using the GPP model to estimate MTBF for
various run time and calculate throughput
• The possible throughput improvement costs
can now be balanced with potential cost
savings
• The improved performance visibility
encouraged a study of the shift change and
restart behavior