GMW 3136 Automotive Safety Glass

The standard “GMW 3136 Automotive safety glass” developed by General Motors describes the product, property and performance requirements for General Motors automotive glass. This standard replaces all General Motors regional glass standards. This standard applies to all General Motors automotive glass types, subclasses and classes. Typical applications include all vehicle front, side, roof rear windows and roof glass. Other automotive glass for mirrors, bulbs, lenses etc. is not covered by this standard.

This standard is the General Motors worldwide glass testing standard. The purpose of this standard is to establish a common testing methodology for glass systems to ensure the continued development and production of a high quality world class system. This is a living standard and any proposals or revisions are reviewed and updated annually by the fixed glass global subsystem leadership team.

The general requirements in this standard are determined as follows:

• Any deviations from this standard require General Motors engineering approval.
• Vehicle windows must comply with the federal motor vehicle safety standard and the United Nations Economic Commission for Europe regulations. Depending on the place of production and sales market, windows may require other regulatory certifications.
• For identification purposes, an indelible monogram must be easily visible from the exterior of the vehicle. The exact location of the marking must be shown on the component drawing or mathematical data.
• Viewing conditions:
  • The subject should be viewed in the glass mounting position.
  • Unless otherwise stated, the observation distance should be between 1 m and 4 m.
  • The lighting system should be diffused daylight D65. Light illumination should not exceed 900 lux.
  • For grid panels the background should be dark grey to matte black. Projected light works should use a white surface.
  • The visual inspection time for each glass position is 60 seconds.

In this standard, the product requirements are determined as follows:

• Light transmission: Must meet the light transmission supported by the data generated by CG6061.
• Glass chemical resistance: There shall be no objectionable deterioration or surface discoloration when tested according to fuel resistance standard GMW 14333 or liquid resistance standard GMW 14334.
• Mechanical strength and stress: Visible defects that affect glass strength are not permitted. Glass manufactured from tempered or heat-strengthened glass must be pre-stressed and free from any microcracks, surface defects, edge defects, or abrupt changes in stress profile/pattern that could compromise its optical properties or mechanical strength. Stress values ​​are measured with General Motors approved stress measurement equipment. To measure the compressive stress of laminated glass, it is permissible to cut the enamel print in such areas that are closed after assembly.

To protect the laminated windshield from mechanical forces that may be imposed on it during transportation and installation, laminated safety glass shall be manufactured with a defined tension system in an edge area up to 20 mm wide. The edge compressive stress in laminated glass shall be at least 8 MPa. For edge compressive stresses greater than 55,2 MPa, a comprehensive process control plan including scribe or sandpaper abrasion testing shall be approved by General Motors. The maximum tensile stress at any location in the laminated glass shall be no more than 7,0 MPa. Abrupt changes in stress levels shall not be permitted.

All class F thermally strengthened laminated glass requires a minimum surface compression of 34,4 MPa in each layer of the laminate. Acoustic properties of class F glass

• Glass distortion levels: Scribing lines on windshields and rear lights must run vertically. Side windows must have a horizontal scribing line orientation. If the curvature of the glass requires a different scribing line orientation, this must be agreed with General Motors and specified on the component drawing.

The GMW 16500 standard applies to zebra tests. All lines must be continuous. A distortion limit pattern agreed upon by General Motors and the supplier must be approved and retained as the primary limit pattern. Side glass such as door glass, quarter windows or vent windows must not have any distortion from the edge of the glass or from obscuration within the 25 mm exemption zone. All lines must be continuous and the distortion of the black grid lines on the screen caused by the glass must not exceed plus/minus 5 mm.

In general, verification of individual components must comply with all requirements of this standard prior to initial sample approval. The supplier must work with General Motors to determine and define the details of the verification methods, procedures, and instrumentation to be used when performing verification on glass and must determine the methodology to be used to validate the results. All subsystem-level verification is conducted on production glass mounted in a General Motors-approved test case simulating an actual in-vehicle installation. Verification is performed in accordance with the GMW 3600 standard.

Glazing is validated by the following process activities:

• Design failure mode analysis
• Process failure mode analysis
• Peer reviews and design control process
• Material verification process
• Mold flow analysis
• Product verification process
• Verification test program
• Fastener verification process

Any damage caused by improper packaging or transportation is the responsibility of the supplier. Vehicle windows must be delivered in such a way that no damage occurs during transportation. Packaging must be designed so that the parts can be easily removed for use at the assembly center without damage. The orientation of the parts is specified on the component drawing.

Our organization has a strong workforce that closely follows global developments in science and technology and continuously strives for improvement. Among the numerous tests, measurements, analyses, and evaluations provided for businesses in various sectors, are testing services compliant with the “GMW 3136 Automotive safety glass” standard.