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PPAP - Production Part Approval Process

The Production Part Approval Process (PPAP) is a process specifying general requirements for the approval of a production part. This achieves a level of standardisation in the product sampling process. This standardised PPAP process makes it possible to provide evidence that the supplier commissioned has understood the product requirements and has put an appropriate quality plan in place.

PPAP divides the sampling process into five different levels (submission levels) with Level 3 being regarded as standard where the customer has not indicated any specific conditions in respect of the sampling level.

Level 1: this level requires a part submission warrant (PSW) and, for specific parts, the report for the approval of appearance-dependent products.
Level 2: this level requires a part submission warrant (PSW), sample parts and some supporting data.
Level 3: this level requires a part submission warrant (PSW), sample parts and full supporting data.
Level 4: this submission level requires a part submission warrant (PSW) accompanied by data specified by the customer.
Level 5: the final level requires a part submission warrant (PSW), sample parts and full data. There must also be supplementary supporting data held available for inspection at the production site.

PPM Parts Per Million

Defect rates as agreed between customer and supplier.

Process-FMEA (P-FMEA)

Situations triggering a Process FMEA

- new constructions, technologies or processes
- modification of an existing process
- the use of an existing process in a new environment, at a new location or for a new application

- the entire process is broken down into its sub-processes / work steps / workstations
- detailed description of the contents of the process with the existing sequence of process stages observed
- description of the specific product features to be created in the relevant stages of the process
- derivation of potential failures from the content of the process, with reference to the possible causes of failure from the 5 Ms: Man, Machine, Material, Material environment and Method.
- description of the consequences arising out of the failure in conjunction with the FMEA Design details
- assessment of the potential risks and production of a ranking list of risks
- derivation of optimisation measures and production of a list of measures
- presentation of potential for optimisation based on an assessment of the targeted final situation.

Process Capability Indices

1. Short-term capability or machine capability
cmk > 1.6 at +/- 5 Sigma (50 parts in 10 random samples)

2. Provisional process capability (pilot series)
ppk > 1.67 at +/- 5 Sigma (20 random samples x 3 parts)

3. Long-term process capability
cpk > 1.33 at +/- 4 Sigma (20 days, 25 random samples x 5 parts)

4. Zero failure production
cpk > 2.0 at +/- 6 Sigma

PV 3307

The testing device composed of finished parts or testing plates is compressed in accordance with the testing diagram (see illustration) in the middle range, to 50% of the initial thickness. The testing medium is selected to match the practical range of application for the relevant product. Storage can be at room temperature, increased temperatures, under the effects of liquids or the like. Standard testing times are 22 hours, 46 hours and 94 hours.

Samples stored at higher temperatures are allowed to cool after having been removed from the oven, at room temperature and still under pressure. Measurement is carried out 5 seconds after the pressure is released.

PV 3330

This special permanent set test is related to the intended application for the O-ring to be tested. Depending on the ring thickness, the compression figure should be between 30% and 50%, usually 40%, however this should be specified on the drawing. The test temperature depends firstly on the temperature resistant properties of the material for testing, and secondly on the long-term temperature to which it is exposed in service.


PWIS-free means that a material is free of paint-wetting impairment substances. The requirement PWIS-free includes a silicone-free requirement.

The PWIS-free requirement is applied mainly in the automotive industry. Products which exude or have attached to them substances like silicone, wax or stripping agents may not be used in production stages prior to the painting process, as contact with these substances gives rise to paintwork flaws. PV 3.10.7 is a rapid test to check PWIS-free condition.