TPT September 2020

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AR T I C L E

Xiris Automation

4) Reduced scrap from earlier detection of defects In a tube mill, production scrap can come from just about anywhere: tooling wear, bad material inputs, out-of- maintenance equipment or a process that is out of control. Regardless of where it comes from, the creation of scrap costs tube fabricators a lot of money and time. As raw material accounts for the majority of the cost to make a tube, reducing the scrap rate by even a fraction of a per cent can provide substantial savings to the tube fabricator. Traditionally, defects are found on a tube mill at the end of the production line by existing non-destructive testing (NDT) equipment or alert operators. By placing an automatic weld inspection system right after the weld box, defects or weld zone variations can be detected earlier in the production process and can be removed from production prior to further value being added to defective products. By detecting the defects automatically right after the weld box and not manually by an operator or inspector at the end of the line after cutting or bundling, a complete length of tube can be saved by responding faster to the out-of-control process. The result is material savings of scrap tube because the process can be brought in control sooner, avoiding producing extra lengths of defective tube. 5) Customer returns What is the cost of customer returns? When a customer refuses to accept a shipment due to a quality problem, the cost escalates as soon as the tube leaves the plant. The cost of customer returns includes all product that gets returned from, rejected by or credited to a customer. It also includes the expense of sorting, investigations, meetings, reporting, shipping, handling and containment. The tube producer may have to rework the product until it meets customer expectations, scrap it, or worse, send a team to the customer’s site to inspect each piece manually. By adding weld inspection into a tube production line, the rate of defect detection will be higher as the weld inspection system will be able to detect, at a high level of accuracy, defects that are not easily detected by NDT equipment or manual operators. With higher defect detection rates, better quality product will be shipped, ultimately reducing customer returns. Deriving value from tangible savings

By using a weld inspection system that can accurately measure weld bead geometry and tube profiles, it may be possible to reduce the number of micrographs taken for each line qualification from a sample made for 100 per cent of every change over to a lower, statistically relevant percentage. The net result is that fewer line qualifications are required, leading to fewer tests (eg micrograph samples) performed in the lab, saving both lab time and lab personnel costs. 3) Reduced mill downtime Tube mills require a large capital investment that often gets amortised over a number of years. Even assuming that a mill is written down over an extended period, such as ten years, the total cost of running a mill can be substantial when including the hourly amortised cost of the mill, the operating costs and related personnel costs. Not surprisingly, minimising mill downtime is always a priority for tube producers. When a tube mill stops for planned events (such as product change overs, mill qualification, planned maintenance), or unplanned events (such as equipment failures, material input problems, shortage of operators, unscheduled maintenance), production stops. For most tube fabricators, downtime is the single largest source of lost production time. While there could be many reasons for a mill’s downtime, focusing attention on the constraints of the mill to ensure optimal use of resources is the most direct route to improved productivity. When manufacturing processes get out of control on a tube mill, common trial and error solutions typically prolong the time needed to correct the process. The result is high wastage and repair costs. In contrast, by implementing automated tools such as an automatic weld inspection system, mill downtime can be reduced by improving the use of resources needed to keep the process in control. With this equipment, tube fabricators can get a better and more advanced warning of process issues that are moving out of tolerance so that the mill does not have to be shut down to fix major tooling or welding issues.