Renault D44 3150 Plastics Marking Resistance (Scratch Resistance by Polishing)

The standard “Renault D44 3150 Plastics marking resistance (scratch resistance by polishing)”, developed by the French automobile company Renault, describes a procedure for determining the marking resistance of plastics used in the composition of interior trim parts (dashboards, rear shelves, etc.).

This test method is applied to reproduce the effects obtained when plastic parts rub against each other, come into contact with hard objects or come into frequent contact with passengers. This contact causes a local increase in brightness. This method is applied to dark-colored (such as black, gray) polypropylene (PP) or polyethylene (PE) samples.

The test consists of subjecting the surface of a flat sample to linear friction of an indenter. Marking the test piece causes a change in the brightness of the area under test. The instrument is moved parallel to the surface of the sample and perpendicular to its length.

Equipment used in the tests includes:

• The test apparatus consists of a reciprocating moving arm. It is connected to the motor by a connecting rod-crank system which includes adjustment of the stroke and the speed of movement of the moving arm. Unless otherwise specified, the recess stroke is set for 101 plus/minus 3 mm of linear movement and the speed of movement of the support in the forward or reverse movement shall be of the order of 20 seconds, corresponding to 1 minute plus/minus 1 second for 1,5 reciprocating movements. A support with a recess screwed on one side (350 g plus/minus 10 g) and an overload on the other side is held at the end of the arm. The total mass of the equipped support shall be 1100 g plus/minus 20 g with overload and indentation. The support shall be kept perpendicular to the base throughout the test. The average linear speed of the apparatus shall be between 70 mm/s and 80 mm/s.
• The indenter is a 7 mm diameter hemispherical steel tipped scriber tip. It is screwed into the threaded hole at the end of the slide axle. The tip is subjected to a visual inspection before each test campaign.
• The base must be integral to the testing machine and allow the specimens to be immobilized during testing. It must also allow for precise offsetting of the specimens.
• A conditioned room is a room conditioned at a temperature of 23 degrees plus/minus 2 degrees and a relative humidity of 50 percent plus/minus 5 percent.

The test pieces should be flat and have a rectangular surface area of ​​at least 60 mm x 100 mm. Wait 1 week after injection before starting the tests and do not touch the surface to be drawn.

The test method is schematically shown in the standard. It consists of placing 80 identical lines side by side to measure the difference in contrast. This should be done in a conditioned room. It is necessary to observe the direction of the lines on the plate suggested in the figure. The tip should make only one pass on each line, but one cycle of the device corresponds to one full rotation of the motor axis, which in turn translates into one revolution of the instrument arm. To make only one outward movement, the instrument must be brought to the end of its stroke by hand, by turning the connecting rod. If the device is programmed to perform one cycle, then it will only do half of it.

The test piece is offset by 0,5 mm, then the process is repeated until 80 parallel lines are obtained on the test piece. The 80 lines should be made in the same direction. After each pass, the marking tool should be returned to the starting point by hand to avoid scratching the plate in the opposite direction.

Our organization, which has been trying to support businesses from every sector with its testing, measurement, analysis and evaluation studies carried out in a wide range for years, has a strong staff that closely follows the developments in the world in the field of science and technology and constantly improves itself. In this context, testing services are also provided to businesses in accordance with the "Renault D44 3150 Plastics marking resistance (polishing scratch resistance)" standard.