Case of a company that had high wire drawing speed for upholstery and lost its ability to run fast.
This company bought a new single high wire drawing speed machine with 12 dies for upholstery spring wire with an installed capacity of near 900 tons/month (given the sizes mix).
The machine can run at 4920 foot/min (25 m/sec) the 2.18 mm.
Headquarters abroad buys the wire rod and delivered to the wire mill.
Here the purchasing criteria is steel grade, diameter and price, and therefore the steel quality is very variable: from the best available to the worst in the market.
In less than 6 months they bought for this single machine from seven different mills.
Problems with high wire drawing speed.
The problem with this practice is that all suppliers see the customer as a “one time customer” and very often they deliver the leftovers of other regular customer’s heats with the associated problems:
- Too many coils from different heats.
- Very high spread chemical composition and therefore very broad tensile properties.
- The coils often rust and corrod because they spent much time outdoors in the supplier’s yard.
- Mistreated coils that cause snarls on the pay-offs.
- Mechanical damage due to several movements on the supplier’s yard.
- Reclassified coils to a lower or upper steel specification.
- A slightly low (in carbon content) 1060 can be reclassified as 1055.
- There is a high probability for the supplier to send, on purpose, defective coils since the chance for a complaint is very low or inexistent.
- The quality was, in general, not good enough for running at 4920 foot/min (25 m/sec).
- So the actual output went down to around 500 ton/month instead of 900 ton/month.
- The productivity could be sometimes at 100%, it is at 4 920 foot/min (25 m/min) whenever they get good wire rod, they are able to run at theses speeds, but the overall efficiency fell to 55%.
It advisable to get the wire rod from a reliable supplier to maintain the quality of your final product.