Percentage by weight of use of reprocessed thermoplastic material
UL has been requested to provide information and clarification to the information technology equipment (ITE) industry on the maximum allowable percentage of reprocessed or regrind thermoplastic material that may be used in a manufacturer's molding process of thermoplastics used in equipment subjected to UL Follow-up Service. This is an established UL Follow-up Service requirement that is applicable to thermoplastic material utilized in all product categories where specific thermoplastic material is identified in the end-use procedure. It is not a new requirement nor is it exclusive to ITE.
Unless otherwise stated in the Follow-up Service Procedure, virgin reprocessed or reground thermoplastic materials are not permitted to exceed 25 percent by weight of the material that has been dry blended and thoroughly mixed by the molder with the same grade of virgin material. Reprocessed or reground thermoplastic material refers to ground or chopped flash, runners, and non-contaminated rejected parts that were produced by the molder during the initial molding operations.
Materials other than virgin thermoplastic such as thermoplastic elastomers, thermoset and recycled materials are not authorized by UL to be reprocessed or reground for products covered under UL Follow-up Service unless subject to special investigation. These materials are not permitted to be employed in the molding/fabrication of parts, unless the results of a separate investigation and Follow-up Service Procedure coverage indicate acceptable performance for the specific part that contains regrind of these materials.
UL's rationale for the 25 percent limit on reprocessed thermoplastic material is based on input from the plastics industry, where it has been agreed that percentages up to about 25 percent regrind do not significantly compromise the properties of the virgin thermoplastic material. Above 25 percent regrind, the implications on any indices and properties defined as part of the original material certification are unknown without further testing. This philosophy is a key component of UL's Fabricated Parts certification as described under paragraph 8.2 of UL 746D, the Standard for Polymeric Materials - Fabricated Parts, and is described under the current Appendix A, Standardized Appendix Pages for Recognized Component - Fabricated Parts (QMMY2).
To comply with UL Follow-up Service requirements, if the molding takes place at the end product location, the manufacturing records should be made available to the UL representative(s) upon their request, to verify the percentage of regrind utilized. If the molded parts are being supplied from an outside source, and have been accepted in the past based on a certificate of compliance (C of C), UL Follow-up Service field representatives have been instructed to accept the percent regrind information identified on the C of C. The information should declare that the reprocessed material content of the received molded parts does not exceed 25 percent. A procurement requirement on purchase orders to molders including that a conformance statement appear on the documentation accompanying each shipment is also acceptable. This documentation must be traceable to the individual lot(s) of delivered molded parts. All verification information should be formatted in accordance with accepted business practices and comprehensible to the UL representative(s).
Should the component molder have plastic recognized component coverage under the fabricated parts category (QMMY2), further verification will not be required. In this category, the maximum allowable percentage of reprocessed or regrind thermoplastic material requirements are verified at those facilities visited by the UL representatives.