Liberty Speciality Steel produces high value, precision-engineered alloy and stainless steel products for use in demanding sectors such as aerospace, oil and gas, bearings and industrial engineering, as well as bright bar and narrow strip for customers around the world.
Andy Spalding, Works Engineer at Liberty Speciality Steel (Narrow Strip) in Brinsworth comments: “In November 2016, we installed a non-contact inline gauge [thickness] profile measurement system from Micro-Epsilon in our narrow strip slitting line at Brinsworth. The thicknessCONTROL C-frame system has further improved our capability to monitor the strip specifications, allowing us to make improvements to our product quality and consistency.”
He continues: “Prior to installing the system, we were manually inspecting strip using micrometers by taking measurements at various points across the strip. We’re now using the thicknessCONTROL system to measure not only the thickness profile across the strip, but also three key quality parameters: the crown, the wedge and the edge drop. The system enables us to continuously check that the thickness profile and the key parameters are meeting the customer’s specification.”
Compensating for oscillating strip
Before selecting the thicknessCONTROL system, Liberty Speciality Steel considered various other thickness measurement systems, including both contact and non-contact systems. As Andy Spalding recalls: “We chose Micro-Epsilon’s system primarily due its cost and how technically sound it is. Although most thickness measurement systems can handle the manufacturing tolerances that we work to, the strip does have a tendency to oscillate slightly as it’s being processed, which can affect measurement accuracy. We therefore worked closely with Micro-Epsilon to devise a C-frame mounting arrangement that utilises a series of plastic wear plates that help to restrict the movement of the strip to a maximum of 60mm as it’s being rolled. This means our measurements are reliable and accurate.”
According to Spalding, rolling specialty steels is a very challenging process. The strip materials can quickly wear the rolls, which in turn, affects the profile gauge of the strip. “In order to minimise the effects of roll wear, we used to roll a maximum number of slabs, between 18 and 22 before the rolls would need changing. Now, with the thicknessCONTROL system, we can analyse the measurement data and make a decision whether to extend the number of slabs beyond 22, before the roll wear will start to affect the final quality of the strip produced.”
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