Standards Development

Scope

This document specifies the general principles to be followed when test specimens of thermoplastic materials are prepared by laser-based powder bed fusion, which is also called laser sintering. The laser-sintering process is used to prepare specimens layer upon layer in which thermal energy selectively fuses regions of a powder bed. This document provides a basis for establishing reproducible sintering conditions. Its purpose is to promote uniformity in describing the main process parameters, build orientation of the sintering process and also to establish uniform practice in reporting sintering conditions.

The particular conditions required for reproducible preparation of test specimens which will give comparable results will vary for each material used. These conditions shall be agreed upon between the interested parties.

Purpose

There is a clear need of this standard in the industry where AM is being increased as a method for manufacturing large number of parts. So far, the samples for testing (tensile, flexural, impact, etc) have been based on existing standards developed by other ISO, ASTM, CEN committees. Everybody agrees that the specific characteristics of the AM parts require of an adapted standard for the test specimen definition. In 2010, the sub-committee of ISO for thermoplastics (ISO TC61/ SC 9) approved the standard ISO 27457-1:2010, which application was focused on specimens of plastic parts made by laser sintering. One year later, ISO TC261 started the activity in 2011 with the global scope of developing standards for AM, where laser sintering (under the category of powder bed fusion) was part of the different technologies involved. At this point, with the objective of having one set of AM standards, to be used all over the world, in the general assembly of ISO TC261, ISO TC61, and ASTM F42, was decided to work together in the development of additive manufacturing for plastics. This is the best way to avoid duplicated and even contradictory standards with the corresponding negative effect in the global industry. ISO TC261 has undertaken the task of coordinating the revision of ISO 27457-1: 2010 with the collaboration of experts nominated from the three mentioned groups and with the objective of having the highest quality and level of consensus in this relevant standard. This will be delivered in the form of a Standard. The aim of this document is to revise the existing standard ISO 27457-1:2010, developed in ISO TC61/ SC 9 “Thermoplastics”. This standard, titled Plastics - Preparation of test specimens of thermoplastic materials using mouldless technologies-Part 1: general principles, and laser sintering of test specimens“, refers to preparation of test specimens manufactured by laser sintering. This laser sintering technology is under the scope of ISO TC261 as it’s considered as an additive manufacturing technology in the category of powder bed fusion. The new work item will include a revision of the mentioned standard to be adapted to the general agreed structure between ISO TC2617ASTM F42 , starting from the document from ISO TC61/ SC 9 and with the participation of experts from ISO TC261, ASTM F42 and ISO TC61/ SC 9.The revised standard also will adapt the document to the standard terminology for AM, coordinate systems of the equipment as well as process parameters and conditions to define and prepare the test specimens for testing. Coordination with WG2 (Process, equipment) and WG3 (testing) of ISO TC261 will be carried out. The proposed standard is the first part of two where the second part will include the testing process of specimens and parts.