PFA

(Production Flow Analysis)

At The Ohio State University, I received federal funding from 2004-2012 to develop the methods and software for implementing Job Shop Lean in custom forge shops that supply forgings to the DOD (Department of Defense) and DLA (Defense Logistics Agency). These custom forge shops are job shops that produce small lot sizes of a variety of forgings that are needed to maintain legacy weapon systems. So they had little in common with an OEM like Toyota! My sponsor was intrigued by the idea that Lean would be implemented differently in job shops, compared to how it is implemented at/by Toyota in their assembly factories.

Luckily, at that time, I was doing research on Group Technology and Cellular Manufacturing. Luckily (again!), just around that time I had learned Value Stream Mapping (VSM). VSM is a simple and effective method to plan the implementation of Lean in high-volume low-mix assembly facilities and other repetitive work environments. But it fails to handle the complexity of any job shop! So right there I knew that there was need for an approach to guide a job shop to adopt, adapt and extend Lean as embodied in the Toyota Production System.

At the outset,  I noted the following key parallels between Lean and Job shop Lean:

LEAN	JOB SHOP LEAN
Assembly Line	Manufacturing Cell 1
Single Product 2	Part Family 3
Make-To-Stock 4	Make-To-Order 5
Pull Scheduling	Push-Pull Scheduling 6

Based on the analogy between Value Stream and Part Family, it was a no-brainer to use the method of Production Flow Analysis (PFA) to form the part families and implement a manufacturing cell to produce each part family. But even more significantly, the efforts made to overcome the constraints and obstacles to implement each cell became the Continuous Improvement strategy for implementing Job Shop Lean one cell at a time.

                                               

1 The cell could be a flow shop, a job shop or other multi-product multi-machine manufacturing system.
2 Mixed model assembly lines can handle a variety of product variants .
3 A part family consists of similar parts whose routings contain some or other combination of machines drawn from a limited group of dissimilar machines that can all be co-located in the same area.
4 Production scheduling is done using heijunka.
5 Production scheduling is done using a Finite Capacity Scheduling tool that can handle due dates, resource (machines, labor, materials, dies & molds, etc.) constraints, etc.
6 Work Order Releases are controlled using a Finite Capacity Scheduling tool to determine how many orders can be released at the start of any shift before the bottleneck(s) show buildups of queues beyond acceptable WIP levels.

 

 

PFAST

(Production Flow Analysis and Simplification Toolkit)

PFAST (Production Flow Analysis and Simplification Toolkit) is the software package used to implement PFA hierarchically at each of the four levels of a typical factory:

Factory

[A factory can have many shops]

↓

Shop

[A shop can have many cells]

↓

Cell

[A cell can have many machines]

↓

Machine

[A machine can process many parts]

 

Additional Reading

Please click here to access the presentation Reduction and Simplification of Material Flows in a Factory – The Essential Foundation of Job shop Lean.

Website to Purchase PFAST
If you are interested in purchasing a single user license 7 of PFAST, please click here.
Thank you!

 

[7] This license is NOT transferable to another computer.