Since its establishment in 1992, Laserplus Oy has been involved in customized manufacturing and laser processing systems. The company has launched a new laser machine for automating material testing procedures.
Automated manufacturing system
Laserplus Oy has introduced an automated laser-based specimen manufacturing system (ASMS) into Outokumpu Stainless Steel Mill in Tornio, Finland. The use of laser processing has provided a more cost effective and less labour-intensive way to producing specimens for material testing.
Manufacturing a large number of the specimens of various shapes traditionally involves a combination of CNC machining and manual cutting, but this does not provide the tracking of individual specimens of test material, except within individual test sheets.
The improved ASMS method involves the use of laser technology to: (i) automate the manufacturing phases; and (ii) integrate the automated laser system for the entire quality assurance process.
The ASMS provides individual specimen tracking by reporting, for example, specimen production rates, problems in specimen production or specimen marking and cutting times. By following up the information available in reports, quality assurance personnel are able to control the entire process.
Advantages of laser technology
Non-contact laser processes are fast and precise. High repeatability in specimen cutting tolerances ensures reliable tensile test results. Clear and machine vision readable laser marking (text, logo, 2D-code, raster) provides individual traceability for test specimens. Operator intervention is minimized, removing the possibility of the human error in making the specimen.
A laboratory is able to receive straight and flat specimens for tensile testing. The geometry of the specimen is symmetrical, because no machining jigs and re-clamping is required. The laser process without CNC machining does not cause strain hardening and increase in the grain size of the specimen material. By laser cutting the heat-affected zone or thermal effects are minimized and damage to surrounding areas of the work piece is prevented. Laser technology provides the flexibility to manufacture multiple test sample geometries. The manufacturing system allows the rotation of the specimen geometry (for example 45 or 90 degrees) related to the rolling direction.
The ASMS includes test sheet loading, identification, laser marking, laser cutting, specimen sorting and scrap removal phases. After loading the test sheet into the entry section of the ASMS, the bar code is identified from the test sheet. Simultaneously the specimen manufacturing information is downloaded. After identification phase and prior to laser marking, the width, length and thickness of the test sheet is measured. This information is also downloaded. The set up of the test sheet contains marking data, different geometries and quantities of specimens; typically three to ten specimens will be required. The software decides the specimen nesting positions based on production database and measurement information.
The data set up of the test sheet
The laser marking of the specimen follows the set up from the plant production database. The marking of the specimen and cutting positions are coordinated with each other. The laser cutting is implemented with two cutting heads. The thickness of the test sheet can vary from 0.5 mm up to 12mm.
The ASMS was designed bearing in mind the location of the specimen tensile test workstation and the layout and functionality of the ASMS with regard to the future use of a robot next to the sorting table to serve that table of the tensile test workstation.
Several different laser source types are available on the market for various applications. For the ASMS, which is designed for 24/7 operations and which places a high demand on beam quality, operational reliability and space requirements, a compact CO2 slab laser was selected for the cutting application. The laser beam delivery optics directs the beam to one of two cutting heads. The selection of cutting head is based on the thickness of the material to be cut.
A diode-pumped Nd:YAG-laser device was selected for the stainless steel marking. This laser type is particularly well suited for marking metals. Laserplus Oy equipped the marking head with a specially designed guard for safety reasons.
Commissioning was successfully completed in May 2006 and the line is currently in production as a part of the Outokumpu Stainless Tornio quality assurance process. The line is connected to the manufacturing process network and produces the test samples based on the customer database requirements. The operator interference for the automated system is only three hours in an eight hour shift.
Metal specimens are automatically marked, cut and sorted for material tests as part of the quality assurance process. In this way the production of test specimens is faster and more cost effective than manual methods. Based on the modular design, the ASMS handles stainless, carbon steel, and aluminium products including hot and cold rolled strip coils, plates and sheets with various capacity requirements. It runs unmanned and its operation is fully incorporated into the production at Tornio plant with the specified capacity.
Contact: Veli-Pekka Immonen