Title: Inspect Parts and Compare Against Acceptance Criteria
Course: PW-Course-Import-Test > Section: Module 5: Performing an Inspection

Module 5

This is where the actual inspection happens. Types of inspection can vary depending on the feature and specification to be verified. However, as discussed in previous modules, the majority of inspections fall under either dimensional, visual or functional.

For each part you inspect, you will record the inspection results on the inspection form. Depending on the company you are working for, this inspection form can be electronic or a physical paper form. If it is an electronic form you enter the measured values in the computer and if it is a paper form you write in the dimensions using a pen.

Every time you measure and enter a dimension you compare it against the acceptance criteria. The dimension can be within the specification or outside it. If the dimension is outside the specification then the part measured fails for that dimension.

Now let's look at an example. Say that the width specification for a part is 0.25 +/-0.05 inches. This means that the width of the part can vary from 0.20 to 0.30 inches. Say for example that the sampling plan requires an inspector to measure eight parts. The dimensions measured are entered by the inspector in the table below. Each time the inspector enters the dimension they verify the dimension against the acceptance criteria.

Measured Dimension | Pass/Fail
0.24 | Pass
0.23 | Pass
0.24 | Pass
0.20 | Pass
0.27 | Pass
0.31 | Fail
0.24 | Pass
0.25 | Pass

In the above example, one of the dimension measured 0.31 inches. This dimension is outside the specification. This dimension cannot be bigger than 0.30 inches. Since the dimension of this part is 0.31 inches it does not meet the specification and fails.

This example Inspection Form was filled out at receiving inspection for part number 101-222-001, lot number 00055211 and batch quantity of 80. Using the sampling plan that the drawing called for, there were a total of 13 samples that the quality inspector measured for dimensions 1.250 +/- 0.100 inches and 0.250 +/- 0.010 inches. The dimension measured for these parts were within specification and the inspection has been signed off by two independent approvers.

Following good documentation practice (GDP), the columns that were not used to record dimensions were denoted with a ‘N/A’. The inspector made an error while recording dimension 0.250 for sample number 5. Notice how the inspector has corrected this error using a single line to cross out the error, entered the correct value and then signed and dated the entry.

Review Reports

In some cases, a quality inspector does not have to inspect any part to make a quality determination, but needs to inspect an output of a process. Depending on the output of the process the quality inspector can make a determination if the process is in control. Take for example a manufacturing room that has be to within a particular humidity range, day and night. The quality inspector can make frequent visits during the day to verify that the humidity of the room is within the requirements. But this can be time consuming and resource intensive, especially at night time when the quality inspector staff is either reduced or not present. In such cases, the company has an option of using a computer or any other device that will generate continuous data.

An economical way is to use a chart record. The chart recorder records data on paper. The paper is passed under a pen and the pen is deflected in proportion to the signal. The result is a graph or chart of the data. Chart recorders can also record information in a digital format for download to a computer.

There are many other forms of reports recording different outputs that an quality inspector can be required to review depending on the nature of the process.

Accept or Reject Product

You have inspected all the parts required by the sampling plan; you have also documented your inspection on the inspection form; now what next? You are almost done, but not yet. The additional actions that you have to take depend on your inspection results.

In the inspection form you indicated if the part passed or failed for that particular dimension. If everything in that ‘Pass/Fail’ column is marked as ‘Pass’ then your inspection is completed. All you need to do is gather all the documents you used in the inspection and release the parts for production use. The way parts are released for production use and the location where the completed inspection documents are stored will depend on the company procedures. Some companies may also require that you stamp the completed inspection form with a green stamp that says ‘Approved’.

On the other hand, there can be a situation in which more samples fail the acceptance criteria than allowed by the inspection plan. If this situation arises, then you cannot accept any of the parts in that lot. The entire lot has to be flagged as rejected and the moved to a place where it cannot be used. The inspection documents will get a red ‘Failed’ stamp and you would initiate what is called a non conformance report. We will learn all about this in the next module.