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Stressing the Manufacturing Line.

We have written a few articles that provide a glimpse of what it takes to develop and manufacture products for the automotive industry.The propulsion system does not matter, whether electric, or petroleum, there are design, tooling, and manufacturing and logistics considerations throughout.  We have taken an overview of the Advanced Product Quality Planning (APQP) process as well as the details of the Production Part Approval Process (PPAP) and the Failure Mode Effects Analysis approach (SySFMEA, DFMEA, and PFMEA).
Today we are going to review the production runs we use to learn about our proposed manufacturing processes.  On the way to our production run start, we will likely exercise the manufacturing line.  We say likely, because what we choose to do will be predicated upon our assessment of the situation.
For example, if this is a minor adaptation to an existing manufacturing line, we may decide more than the initial sample approval (ISA) run is too much or a waste of company time and resources and the expense is not commensurate with the risk

Some of the Inputs

There are many things that go into the elixir that results in the end manufacturing line. We provide a brief list of questions we will ask ourselves below:

– How many parts do we need to build per unit time (annually, weekly, daily)?

– What is the product’s Functional Safety, ISO 26262 level (Automotive Safety Integrity Level ASIL)?

– Is the demand continuous or periodic?

– How is the supply chain constructed? What is the model the supply chain logistics?

– What is our inventory model?

– Are there line set up and tear down consequences?

– Is our line continuous or batch?

– What is the desired yield?

– What are our attitudes about scrap and rework?

– What model of inventory do we have or should we adopt?

– What is the manufacturing technical requirements?

– What is the company philosophy and expertise in automation?

– How much of existing equipment can be used or adapted?

– What is the nature of this product compared to other products we manufacture?

– What are the production lot sizes required by the customers?

– Are there outsourced or lower tier assemblies involved? Should we use subassemblies?

– What are the advancing manufacturing technologies of which we can avail ourselves?

Stressing Work Stations

In general, stressing the line as we develop it, is analogous to stressing the product iterations, the early prototype through the final representation of the product.  Every work station, we can execute those work instructions with the people that will be working the manufacturing line.

We can also take specific measurements during this effort, for example, we may conduct a Gauge Repeatability and Reproducibility to understand the impact of a measurement tool and interpretation from those working the line.  This is not about Gauge R & R, just a note that these exercises are done for specific reasons, to learn and one mechanism for learning is the Gauge R&R.

We exercise the individual work stations, configuration and work instructions, to learn about the competency of the portion of the line, the ability of that segment to be able to produce its specific portion of the product.

Figure 2 Photo from Pexels at

Trial Production Runs (TPR)

Trial production runs are when we have the manufacturing line in its entirety set up. This will likely not be the final incarnation, it a first set up of the line.  The trial production run will deploy the line to produce a small batch run.
This is not a stress the line moment, but an opportunity for the operators to interact with the actual line, for us to gather information on the product as it flows through the manufacturing line, control chart starts and any other measurements we deem necessary for our learning.

These limited runs well make it possible to move our paper, theoretical line closer to the actual production line that is capable of meeting the time, throughput, and quality demands.

Run at Rate

The Run at rate happens later in the line set up, at this point we have tweaked the manufacturing line based upon the feedback from the TPR, but these would have been small runs, that would have resulted in some alterations of the manufacturing line.  In this case, we are building a production volume, although it might be smaller than the expected, at the rate that matches the production run, putting the manufacturing line under the stresses that are associated with production.

The parts from the run at rate, can be used as fodder for production validation testing (PVT). The parts off the end of this line might be used to validate the product.  This will consist of a variety of product tests, often environmental and performance, that are performed to assess the manufacturing line’s ability to produce the designed product that meets the customer and the organizations quality requirements.

The parts may also be used as initial sample approval (ISA), where the customer reviews the product, often dimensional and surface treatment expectations (looking for blemishes).  This will be part of the production part approval process (PPAP), which is a collection of artifacts from the design and manufacturing effort.


It is not enough to adequately design the product to meet the customers needs, but we are going to have to produce the product at the volume, and quality expected.  Our approach will be commensurate with product cost and risks.

A good quality product comes from not just the design, but also from how we manufacture the product. Just like design of the product, the manufacturing of the product will influence the quality.

However, it is not only about the quality, but the ability to produce the product at the volume the customer or customers need, and to be able to deliver these in time to keep the manufacturing line up and running. Both of these must be met to ensure for the project and the product meet the expectations.

To develop and deliver a product requires a multitude of talent, from the idea and systems, to design, design for manufacturing and assembly through to production, all orchestrated well to produce the desired product.

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