Statistical Quality Inspection

Statistical quality inspection refers to parameter-controlled values and the quality inspection history of an item. Together, these determine if quality inspection should be performed and how often.

To be able to use statistical quality inspection the item/supplier records must have been specified in 'Supplier. Connect Item' (PPS040).

When receipt is reported in 'Purchase Order. Receive Goods' (PPS300), the good receiving method and the goods receiving flow for each order line are checked. If goods receiving method for the order line is 4 or 5, statistical quality inspection should be performed.

Control logic

If statistical quality inspection is to be performed, the following is indicated:

  • The proposed location is specified as a quality inspection location.
  • The 'Next activity' field in 'Purchase Order. Display Line Transactions' (PPS330) indicates that quality inspection is to be performed.

Conditions

Statistical quality inspection is performed if any of the following conditions are found in (PPS040).

  • There is no item/supplier combination.
  • The 'Standard of approval' field indicates that standard of approval is required and is not reported.
  • The inspection level for the next batch is 1, 2, or 3 on the G panel.
  • The current delivery is a new revision (it differs from previously received orders) and parameters in the G panel indicate that an inspection is to be performed.
  • On the G panel, the minimum inspection interval in days is less than the difference between the current date and the previous inspection date.
  • An inspection should be performed according to the quality inspection plan.

If an inspection is to be performed based on conditions 1-5, the reasons are indicated in the detailed receipt documents in 'Receipt Document' (PPS307).

Inspection level

There are four quality inspection levels:

  • 1 - Intensive
  • 2 - Normal
  • 3 - Reduced
  • 4 - None.

If quality inspection is always performed (not statistical quality inspection), the inspection level is always 2.

Sampling quantities can be connected to different inspection levels (see 1-3 above). This is done by specifying the applicable sample table for the item/supplier combination in (PPS040/G).

Example of a quality inspection plan

For (a) below, the following applies: Periodic inspection should be performed so that only every third delivery is inspected at a reduced inspection level.

For (b) below, the following applies: If a delivery is rejected, the next two deliveries are inspected at a normal inspection level.

These examples result in the following quality inspection plan, as defined in 'Quality Inspection Plan. Open' (PPS340/E):

  • No. of approved batches - level change 1 to 2 No. deliveries: 0
  • No. of approved batches - level change 2 to 3 No. deliveries:2(b)
  • No. of approved batches - level change 3 to 4 No. deliveries:1(a)
  • No. of batches at QI level 4 - without QI No. deliveries:2(a)
  • After QI level 4 - go to QI level No. deliveries:3(a)

Inspection level 2 is also specified in the parameters which refer to the level to apply after rejection (b).

If the above check indicates that quality inspection should not be performed, a check is still made against parameters in (PPS340/F). Here, it should be indicated that inspection will be performed at a determined level if X of the last Y deliveries were rejected. For example, as long as two of the last ten deliveries are rejected, an intensive inspection should be performed.

Quality inspection tasks

Each quality inspection task can be regulated by a quality inspection plan. This means that each task is considered as a unique item.

The tasks are updated in 'Quality Inspection Task. Connect to Item' (PPS080).

Example

An item has two operations. One of them is inspected every other time and the second operation every fourth time. A quality inspection plan corresponding to every other time is then specified for the item. For the operation to be inspected every fourth time, a default quality inspection plan is entered.

Counters for quality inspection plans

If an error is detected afterwards, the counters can be changed so that the next delivery is inspected. This is done by changing the item counters in 'Quality Inspection Task. Update Counter' (PPS082), reached from (PPS040/G). Counters for quality inspection tasks can also be changed in (PPS082), reached from (PPS080).

Note: The inspection and inspection level for the next delivery can also be influenced by the parameter settings in (PPS040/G).

If receipt is performed for an ID and the inspection level for the next delivery is filled in, this is then used and deleted for the item/supplier combination.