AS ISO 27547.1 pdf download

AS ISO 27547.1 pdf download.Plastics — Preparation of test specimens of thermoplastic materials using mouldless technologies
1  Scope
This part of ISO 27547 specifies the general principles of test-specimen preparation using mouldless techniques. Sometimes, these techniques are called “tool-less” methods. Common to all these techniques is the fact that the specimens are produced layer by layer. The shape and dimensions of the specimens are defined in terms of a numerical description using CAD techniques. This computer model of the specimen is “sliced” into layers by means of suitable software. The specimen-preparation process then builds up the specimens automatically, layer by layer, using the computer model and a suitable computer-controlled laser-sintering machine. The three software systems used (for CAD, slicing the specimen into layers and machine control) may be independent systems interfacing separately with the machine or they may be integrated with the machine. This part of ISO 27547 also specifies the general principles to be followed when test specimens of thermoplastic materials are prepared by laser sintering. The laser-sintering process is used to prepare specimens layer-wise by sintering the particles of a thermoplastic powder using the energy of a laser beam. This part of ISO 27547 provides a basis for establishing reproducible sintering conditions. Its purpose is to promote uniformity in describing the main parameters 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 as given in the International Standard for the relevant material or shall be agreed upon between the interested parties.
3  Terms and definitions
For the purposes of this document, the following terms and definitions apply. 3.1 laser wavelength wavelength at the peak intensity of the laser used for sintering Note 1 to entry: It is expressed in nanometres. 3.2 laser power power of the laser beam Note 1 to entry: It is expressed in watts. Note 2 to entry: The laser power is usually different when producing the contour (outline) of the specimen and when hatching the specimen. Both values are therefore reported.3.3 laser mode parameter indicating which of the various electromagnetic standing waves that can be produced in the laser cavity is actually being used in a particular application 3.4 beam radius radius of the laser beam, determined in the way described in Annex B Note 1 to entry: It is expressed in millimetres. 3.5 beam speed speed of travel of the laser beam across the surface of the specimen being prepared Note 1 to entry: It is expressed in millimetres per second. Note 2 to entry: The beam speed is usually different when producing the contour (outline) of the specimen and when hatching the specimen. Both values are therefore reported. 3.6 powder-dispenser speed speed of the powder dispenser as it moves across the specimen-preparation chamber before preheating begins (see Figure A.1) Note 1 to entry: It is expressed in millimetres per minute. 3.7 preheating temperature temperature to which the specimen-preparation chamber is heated before the specimen-preparation process starts Note 1 to entry: It is expressed in degrees Celsius. 3.8 preheating time length of time the powder bed is heated before the specimen-preparation process starts Note 1 to entry: It is expressed in minutes. Note 2 to entry: The preheating time is rather long (approx. 30 min) as it is necessary to have a steady-state temperature which is the same throughout the whole specimen-preparation chamber. 3.9 temperature of the powder temperature of the surface of the polymer powder Note 1 to entry: It is expressed in degrees Celsius. Note 2 to entry: Another important temperature is the controlled temperature of that part of the chamber near the sintered layer. It is also expressed in degrees Celsius.