wastes Archives - CNC Industries

Precision Aerospace Machining and the seven wastes of lean manufacturing (part 5)

The fifth of the seven wastes is the most readily obvious waste – defects. A part or product that is not made correctly and needs to be either re-worked or discarded, is obviously a waste. The time spent on the original part is wasted, the material and other costs are wasted, the time that it takes to re-work or re-make the part is wasted. Overall defects cause considerable disruptions and waste.

Once again high volume work has an easier time of removing defects from the process. the length of the run of a part will justify creating more complex and expensive fixturing to enable quality at the course – so that the part has little or no chance of being produced improperly. Custom inspection procedures will allow quick discovery of any non-conforming parts as well.

In a low volume high mix facility – as a large portion of CNC Industries is, making custom machined parts and precision aerospace machined parts, we cannot spend an extensive amount of time on fixturing – our lead time for the entire first batch of product is sometimes shorter than production companies will spend on a single fixture for a production part. The inspection requirements and quality standards will also vary – sometimes greatly – between parts running through our shop at the same time. We have to ensure that each fixture is made quickly and still performs as it needs to.

Of course defects are caused by a myriad of issues beyond just the fixturing the part correctly. We have many more methods of preventing mistakes and defects before they occur, but I think a more telling evaluation of a companies dedication to eliminating defects is the processes taken when a defect does occur. At CNC Industries, we place great emphasis on root cause analysis and corrective / preventative actions. As we are nearing our AS9100 certification, we are more aware of this need than ever before.

Our Corrective Action System is based on the Apollo Root Cause Analysis and allows and indefinite depth of root cause analysis. We regard and defect as a serious issue and are quick to come to an understanding of the root cause that allowed the defect to occur. With our ERP system, we are able to quickly resolve any ongoing systemic issue and immediately take the necessary corrective action to prevent future occurrences of the issue. Preventative and corrective actions and their resolutions are transmitted throughout the company immediately upon completion and necessary procedural and process changes are automatically updated. All relevant documentation is kept entirely in sync with our digital paperless document system.

The ability to adjust our entire process to address a deficiency in the processes that we utilize allows us to have an extremely low defect rate – and when the very occasional defect does occur we can quickly adapt and prevent the problem in the future.

– – – –

CNC Industries is a Fort Wayne, Indiana based machine shop specializing in precision CNC machining, fabrication and assembly of application-critical and custom machined parts for the Aerospace, Defense, Medical, Industrial and Transportation markets. The company presently employs approximately 55 people.

– – – –

Lean manufacturing and Aerospace Machining, Low Volume / High Mix production

Lean manufacturing is a concept that most businesses strive for and many claim. The primary concept of lean manufacturing is eliminating all unnecessary costs and time associated with production. The primary way most companies will start with Lean is to manufacture parts as fast as possible – to get as much production from each machine as possible. As the cycle time decreases wasted machine time decreases as well. This is a great start to lean manufacturing, but it is also the most common method. Many companies focus on cycle time reduction almost entirely in their lean efforts.

Cycle Time reduction works best in environments where a machine shop is producing the same part for a long duration. This is typically a full production shop and will have dedicated machinery to optimize a single process to the fullest extent possible. In the aerospace machining industry or custom machined parts production we are not producing high enough volumes of many parts to dedicate an entire machine to a single part. As such aerospace machine shops and custom manufacturing shops (or job shops) will face additional difficulties in going ‘lean’.

Adjusting the cycle time down by 10% is not as effective of a lean tool when machine time may only be 60% or less of the time spent on producing a given part. The lower the proportion of machine time to non-machine time in a job, the more important it is to go lean in additional ways. in connection to that – the more often a machine needs to be set up for a new job the more non-machine cost is in the job – for reference a single aerospace machined part may have 5 or 6 separate machining operations each requiring an additional setup on the machine. Transferring the material to different areas, setting up the machine, inspecting the part throughout production, and other items add to the non-machine time at every step.

Over the next few posts I will be looking at the 7 wastes identified in a typical lean manufacturing implementation and how CNC Industries deals with each on in relation to our low volume / high mix work. We have some production jobs as well, but those are handled in slightly different ways, and will be discussed at a later time.

– – – –