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quality control converting
Lee K. HouseMar 8, 20244 min read

What Quality Control Inspections Do Converters Perform?

How does your adhesive converter prevent faulty parts from reaching you?

Quality inspections are necessary for every manufacturing process, but your needs may vary depending on the product. 

At Strouse, all of the parts we produce go through some form of inspection, the thoroughness of which depends on the job specifications. If you’re planning on ordering parts from a converter, familiarizing yourself with the quality control process might help you find a converter who can meet the necessary standards for your process. 

Let’s discuss what goes into quality control inspection so you can make the best decisions for your product.

How Part Inspection Adds Value To Your Process

Simply put, defective parts will cost you time and money. Using a converter that takes the proper manufacturing precautions against part defects will protect you from product failures and a loss of consumer trust. 

What Are Our Inspection Equipment Capabilities?

One of the first things we get asked about inspection as a converter is our equipment capabilities. Inspection equipment helps a converter monitor product for defects caused by tension changes or puckered material.

Extensible materials like foam and polyethylene are more prone to stretching and straining on a machine press. This can lead to issues once the cut part gradually shrinks to its actual size. 

When thousandths of an inch can determine a good part vs. a bad part, it’s crucial to use precise equipment and rigorous inspection processes that suit the customer’s needs. However, not all processes require this level of inspection, so you'll want to account for the level of precision you need. 


Video measuring systems, such as a coordinate-measuring machine (CMM), allow converters to verify part dimensions. The cameras with crosshairs measure the length and width of parts and the distance between them on a roll. 

Instant video measuring systems take a picture and reference that photo to determine the distance between objects. This method is especially effective on smaller parts with many features. 


While it might not include as much in terms of equipment (unless you’re talking rulers, calipers, and micrometers), relative and dimensional testing are essential skills for a converting company. 

Strouse uses a peel-tester and probe-tack tester to measure pressure-sensitive adhesives and performs additional testing on differential liners. 

How To Determine Sample Sizes

If the customer doesn’t prescribe the sampling method, we typically do our sampling based on our unit size (each roll, box, etc.). 

For instance, this could mean pulling a sample once or twice an hour to avoid burdening the operator but still keeping an eye on the process.


The Acceptable Quality Limit (AQL) sampling standard determines the acceptable number of rejected parts before the lot is considered unfit (AQL-1 is standard for paramount checks, but 2.5 has more relaxed requirements).

Certain customers prefer different types of sampling criteria, such as ANSI, Z1.4, or Z1.9 statistical plans. Other popular sampling methods include: 

  • The Squeglia c=0, A.K.A. the “zero defect” or “zero acceptance” plan takes fewer samples, but a single defect will result in throwing out the lot (ex. ANSI could mean sampling 1,000 parts per lot, but Squeglia would be more like ~29 parts or something to that degree). 
  • The FAIR (First Article Inspection Report) comes from the aerospace industry and focuses on product construction and evaluation (measurement data).  
  • PPAP (production part approval process) comes from the automotive industry, but different industries have co-opted one or the other. The PPAP contains more supporting documentation- process flow, control plan, measurement system analysis, for example, as well as measurement data and analysis from the parts themselves. 
  • The last sampling strategy is modified cluster sampling, in which we look at the end of the roll and check the parts for accuracy. This leads to way fewer checks per lot.

Quality Control Inspections in Production

At Strouse, we ensure that there are about four points of inspection before, during, and after production.


Before the product runs on the press, Strouse double-checks the measurements, quantity, documentation, material, and more. Once we’ve verified it all, it’s time to run the order. 


Machine operators monitor the process as the press runs to ensure the material moves correctly. This is often done with the help of tension readouts and the controls located directly on the machine press.  

Our operators will inspect as specified or needed to confirm that products meet the customer-specified standard for tolerances. 


At the end of the run, we inspect the parts to ensure they have the proper construction. This means that the adhesive is on the right side of the liner with the correct part dimensions and accurate holes of the right diameter. 

Then, we refer back to our documentation to check the quantities again and perform the packaging and labeling process.


The final acceptance stage is one last look at the packaging and labels to ensure correct spelling and format. 


Each project has its own quality control requirements, so if there’s any doubt about whether a converter can match your needs, you’ll want to ask about it directly. Due to the fact that everything we do is custom, our quality controls for each project are also custom-tailored to our customer’s needs. 

Don’t settle for countless quality mistakes when you could be saving far more on a more accurate, more efficient process. Reach out for a flexible material consultation and consider switching to a more efficient converter today.  


Lee K. House

Copywriter & Content Creator for Strouse. Lee graduated from the University of Alabama in the Spring of 2022 with a double major in English and Spanish.