Merthyr Tydfil Manufacturer Achieves Significant Cost Savings and Environmental
From their UK Headquarters in Merthyr Tydfil, Amnitec Ltd. is a leading manufacturer in design, development, and manufacturer of flexible metal hose and assemblies for the transfer of fluids and gases in extreme environments.
A high-pressure hose system helps solve several issues facing multiple industries including aerospace, automotive, marine and energy industries. these issues relate to flexure vibration, thermal, or pressure-related problems involving liquid and gas transfer.
ASTUTE 2020 and Amnitec’s collaboration aimed to understand the metallurgical construction of a copper to a stainless steel welded joint improving consistency, enhancing the quality of these welds to eliminate leakage and reduce scrap in products that employ this welding method, thereby enhancing productivity and company competitiveness in this niche market.
Challenge
The difference in mechanical and physical properties between stainless steel and copper is considered a challenge to the welding community.
First of all, the two materials have almost 315°c difference in melting points, which make the generation of a joint pool of the two metals extremely difficult. Furthermore, copper and iron are slightly soluble in each other. Therefore, stainless steel will start to solidify and form grain structures while the copper is still in a liquid state, forced between the stainless steel crystal structures.
As the weld cools further, the stainless steel grain will begin to contract due to cooling, causing the grains to pull apart. at this point, the copper is still too hot to add any structural strength to the grain structure; the weld will form large cracks, known as ”hot cracking”.
To achieve the highest quality joint suitable for welding and to ensure an effective joint design, ASTUTE 2020 supported Amnitec to address these challenges and enhance the quality of these welds.
Solution
ASTUTE 2020 and the Amnitec team analysed the welding process and consumables used to achieve the desired project goals. The research identified multiple welding parameters which could be altered: welding speed, interpass and post-weld cleaning and welding filler.
The company successfully altered some of these parameters by identifying the need to shift the joining technology from TIG welding to TIG brazing technique (done at a lower temperature). Changing the currently used CuSn1 to silicon bronze rod (a copper rod, containing 3% silicon and 1% manganese) was recommended and successfully tested at the company. This change had a significant impact on scrap rate reduction down to 6%.
Possible further routes for the company to explore would be looking at: the effect of torch angle , the response of welding speed (path velocity),the use of automatic welding (robot).
Impact
The collaboration between Amnitec and ASTUTE 2020 has led to significant benefits for the company and the environment through improved welding quality and lower weld temperature:
- Reduction of scrap percentage from 10-20% to 6%
- Reduction in production cost and waste
- Decrease in energy consumption, use of raw materials and CO2 emissions
- Increase in efficiency, productivity and competitiveness
