Cleanliness Evaluation Case Study

The Problem:

The wash process consisted of 2 stages, a wash stage and re-circulating rinse. Our customer was faced with multiple process headaches and as a result of these issues resulted in multiple shifts struggling to keep up with production, excessive chemical use, and re-cleaning the parts.

The main issues:

  • Difficulty in Maintaining Acceptable Part Cleanliness
  • Daily Change Outs of Wash & Rinse Baths.
  • Meeting Production Requirements

Goals & Objectives:

Improve Efficiency, Reduce Shifts, Lowered Chemical Cost and Improved Part Cleanliness

Lily Washer Tools:

In the Wash Process Partnering methodology, Lily Products uses a modified Failure Mode Effects Analysis (FMEA), developed strictly for washers, to determine where the wash process could be potentially at risk. The modified FMEA was completed and potential areas of risk were identified. The majority of the items fell into the category of medium to low risks, which were found to be systemic issues that needed to be addressed. These systemic issues, while important, were not linkable to the customers immediate wash problems. A few high-risk items were found, and all of these were related to a residue problem being experienced.

Identification of Residue:

Based on past experience, the customers first impression was that the residue was either cleaner residue, or a combination of cleaner residue and stamping compound. This type of residue would normally indicate that the washer has reached the end of its useful bath life and was in need of a change out. A sample of this residue was collected to verify this assumption.

The sample was sent to an independent lab for FTIR analysis. The lab found that the residue was a type of fatty acid ester. The closest match was lanolin. Nothing in the wash fluid could leave a residue that would yield an IR spectrum similar to lanolin, but lanolin was a component of the stamping oil being washed off the parts. It was concluded that this residue was coming from the stamping fluid, and it wasn't being completely washed off in the current process.

Lily Products Test Development:

This specific parts washer was directed by its customer to use a certain cleaner in their wash process. The issue with this cleaner was that it left a level of soil on the parts that interfered with the customer's process. This was the basic reason why they were needing to change out wash and rinse bath's daily as well as re-cleaning a high number of parts. Our challenge was to show evidence that part cleanliness could be improved through chemistry.

So, we took sample parts back to our lab and tested the required cleaner as well as other potential cleaners. Parts were cleaned in the lab mimicking the customers wash process. The parts were then subjected to a gravimetric analysis to determine which cleaner left behind the least amount of soil.

Figure 1
The customer's required cleaner was leaving more soil behind than other cleaners.

Cleaner 1 and 2 were comparable and showed a large improvement in overall part cleanliness by leaving behind approximately 70% less soil. The data was presented to the part washers customer, and they agreed to have the part washer select the proper cleaner for the process.

Additional testing was done in the washer with Cleaners 1 and 2 to determine if there were any advantages between the two cleaners, along with capability of the customers upstream process requirements.

Going Forward:

After implementing our cleaner recommendation, improved washer efficiency, reduced shifts, and lowered chemical costs were experienced. By reviewing the risks associated with the highest critical issue, our customer was able to return to normal operation. The next step was to address the moderate risk systemic issues. Here is a chart that shows the improvement that has been made in re-cleaning parts.