Quality Assurance - Parker O-Ring Handbuch

12. Quality assurance

12. Quality Assurance
Quality
It is in the interest of Parker to supply products and services
which meet the quality requirements of our customers.Adopting
the definition of DGQ, Deutsche Gesellschaft für Qualität (Ger-
man Society for Quality) it is our policy to produce quality through
selecting the best materials, optimum production methods, se-
vere test procedures and continuous training of our employees
to manufacture quality:
"Quality is the condition of a product or service
which makes it suitable for its purpose and
complying with existing requirements."(DGQ 22, 1974).
Our extensive Quality System is designed to rule out influences
which negatively affect the quality of our products. Product qual-
ity must be produced and not inspected into a finished product at
the final inspection. Our Quality Handbook is a document which
Fig. No. Ref. or
deviation
12.1 off-register
12.1 mis-match
12.1 mold-radius
different
12.2 flash, off-set and
indentation
12.2 flash
12.2 parting line
projection
12.3 backrind
12.6 parting line
indentation
12.4 excessive trimming
12.5 flowmarks
12.6 indentation
- foreign material
Table 12.1 Type and description of mold and surface finish defects
presents our procedures and shows quality assurance from raw
material reception through production processes and storage to
dispatch. It describes the actual techniques necessary to achieve
the requirements.
DIN EN ISO 9001 certified since 1993 and ISO/TS 16949 since
2002.
Evaluation criteria for O-rings
The criteria governing the evaluation of surface defects in O-ring
seals are defined under DIN 3771 Part 4, see Table 12.1. The
size of allowable defects is quantified in Table 12.2 and subdi-
vided into levels "N" (Table 12.2 N) and "S" (Table 12.2 S). This
subdivision corresponds to levels "B" and "A" in the American
MIL Standard 413.
Definition
Upper and lower half of the mold out of allignment.
Upper and lower half of the O-ring out of allignment.
Upper and lower half radius for O-ring cross-section different.
A combination of flash, off-set and indentation.
This film of material at parting line caused by wear of mold corners.
Continous ridge of material on the parting line caused by wear of mold
corners.
A shrinkage at the parting line with a "U" or "W" shape.
Shallow recess at the parting line caused by deformity in mold edge parting
line.
Trimming is excessive only then an out of tolerance situation is brought
about.
A thread-like recess with normal surface texture caused by incomplete flow
and knit of material.
Surface defects which are mostly irregular in shape and caused
by the removal of surface foreign material, imprints of mold
imperfections, mold not completely filled.
All inclusions of foreign material on the surface, including uncleanliness, etc.
187
O-Ring Handbook
Parker Hannifin GmbH
O-Ring Division Europe