"D"

Design Failure Mode and Effects Analysis (DFMEA) - An analytical technique used by a design responsible engineer/team as a means to assure, to the extent possible, that potential failure modes and their associated causes/mechanisms have been considered and addressed.

Design for Manufacturability and Assembly - A simultaneous engineering process designed to optimize the relationship between design function, manufacturability; and ease of assembly.

Design Information Checklist - A mistake proofing checklist designed to assure that all important items are considered in establishing design requirements.

Design Reviews - A proactive process to prevent problems and misunderstandings.

Design Validation - Testing to ensure that product conforms to defined user needs and/or requi- rements. Design validation follows successful design verification and is normally performed on the final product under defined operating conditions. Multiple validations may be performed if there are different intended uses.

Design Verification - Testing to ensure that all design outputs meet design input requirements. Design verification may include activities such as:

Design Review - Performing Alternate Calculations - Understanding Tests and Demonstrations - Review of Design Stage Documents Before Release

Dielectric strength - The measure of a product's ability to resist passage of a disruptive discharge produced by an electric stress; the voltage that an insulating material can withstand before breakdown occurs,

Discs - Flat, round saucer shaped pieces made from rubber or plastic.

Disperse - To cause particles or molecules of matter to separate and become uniformly scattered throughout a medium. In a rubber compound, the particles of compounding ingredients are dispersed in the rubber. In latex, rubber globules are dispersed in an aqueous medium.

Distributor Seals - Sealing rings used to seal in oil and seal out dust, dirt or trash on an automobile engine electric spark distributor.

Double Acting Seals - Seal rings which seal in two direction, on the push and the pull stroke of a hydraulic or pneumatic cylinder.

Duck - A compact, firm, heavy, plain weave fabric made from cotton or synthetic fibers, or a combination of both. Duck is also known as canvas, army duck, belt duck harvester duck, hose duck and shoe duck.

Dumb-Bell (Test-Piece) - In the physical testing of rubber, a strip test-piece is used that is shaped like a dumb-bell, i.e., constricted in the middle and flaring out at the ends, as distinguished from circular or ring test-piece. The dumb-bell is the most commonly used form or test-piece. Dimensions are set by ASTM standards.

Duocone Seals - A special cone-shaped sealing ring.

Durability - The probability that an item will continue to function at customer expectation levels, at the useful life without requiring overhaul or rebuild due to wearout.

Durometer - An instrument for measuring the hardness of vulcanized rubber and plastic. See Shore

Durometer - The most common Durometer. Type A or A-2 is an instrument for determining the hardness or rubber by measuring its resistance to the penetration (without puncturing) of a blunt indentor point impressed on the rubber surface against the action of a spring; a hand and special scale indicate the resistance to penetration 01. "hardness". The scale reads from zero (0) to 100, zero (0) being very soft and 100 being very hard. The Type D durometer has a sharp indentor point and is used to measure varying degrees of hard rubber up to ebonite.

Dust Seals - Seals used to exclude dust from a machine or device.