Cutting edge non contact measuring technology improves bent tube manufacturing processes and delivers a speedy return on investment.
The humble tube can appear in all walks of life in many different guises. Applications can be as diverse as the obvious automotive requirements (such as hydraulic pipes, brake and coolant systems, exhausts, etc.) through to furniture, domestic appliances, electronic goods, and even medical applications such as dentistry. As a result, the demand for ever more cost effective tube production as well as increasing quality control requirements present constant challenges in today’s tube bending industry.
Reaching a high degree of efficiency is one of the main goals for any manufacturing enterprise. Businesses that produce tubes have 4 main areas of costs that have a serious effect on overall production; gauge manufacture and re-certification, materials and scrappage, gauge and material storage, and setup time for bending machines.
In order to minimise and control these costs, several tube bending companies have recognised the benefits of modern measuring technology. The inspection of tubes has traditionally involved purpose made, fixed dimension fixtures, or time consuming labour intensive manual measurement devices such as portable arms. An automatic optical inspection system specifically designed for high speed measurement of tubes, the AICON TubeInspect system, provides a unique solution for inspecting all types of bent tubes.
TubeInspect is a non-contact measuring system, utilising a series of high resolution digital cameras. The tube is placed inside the measuring unit, and in seconds the cameras collect a series of images from various positions, from which the tube geometry is automatically calculated. The tube can be placed in the measuring cell in any aspect, so there is absolutely no need for fixturing.
TubeInspect can provide high precision measurement of tube geometry, and determine setup and correction data for tube bending machines. The time required to inspect a tube is extremely quick – for example, the measurement results for short fuel pipes are available within 3-5 seconds, whereas the inspection of a complex brake pipe can be conducted in less than 30 seconds. The result display is easily understood by all levels of operator, allowing flawless evaluation of the measurement. So how can TubeInspect reduce manufacturing costs ?
Elimination of gauge costs
Before a tube goes into full production, the prototype can be changed many times with respect to its material and geometry until it meets the final requirements. During this process, the prototypes need to be measured, such that individual gauges have to be manufactured for each individual tube – depending on the complexity of the tube, costs are typically between £2,000 and £5,000.
Every time a prototype is changed, the corresponding gauge has to be adapted which can take several days (including CMM inspection for every modification), leading to additional costs and long delivery lead times that are usually unacceptable to the customer.
Using TubeInspect, it is possible to completely remove the need for manual gauges. The operator simply enters the new data (XYZ or Push/Bend/Rotate data) into the database of the system, and within minutes the measurement of the prototype part is complete. TubeInspect works as a virtual gauge providing measurement of both prototype and series production tubes.
The possible savings in series production can be easily shown with a simple example involving a relatively small bending company that has to manage 5 new products per year, requiring 5 gauges at a typical total (minimum) cost of £10,000. The annual maintenance and re-certification of these gauges amounts to around £500 per gauge. By using the flexible TubeInspect instead of gauges, savings of at least £10,000 are generated within the first year (as no new gauges have to be acquired). In the second year, the savings are £12,500 as this includes both the maintenance costs for the gauges of the previous year (5 gauges @ £500) plus the investment of £10,000 in five additional gauges for new products. Accordingly, the saving each year increases by a further £2,500, and can be summarised as follows;
These savings are exemplary of a fairly small tube bending operation, and will be increased even further as recertification and maintenance of all existing fixtures can also be eliminated, typically £20-50,000 every year. For a large bending facility, it is easy to see how these figures will quickly spiral upwards.
Savings by reducing machine setup times
During series production, regular setups of bending machines are frequently required, for example when a product is changed. This usually requires the intervention of experienced staff to attend to the setup, involving great skill that can sometimes take several hours in the case of complex tubes – meanwhile, production on that machine stops. It is at this point that TubeInspect can really bail you out, as the measuring system provides quantative correctional data within a few seconds that can be automatically transferred to the bending machines.
As a consequence, machine setup is completed within minutes, even by unskilled operators. The savings can be easily demonstrated by considering a small tube manufacturing plant that is common throughout the industry that utilises flexible manufacturing with 4 bending machines to produce and deliver small batches. Over a typical production period of several days, every bending machine is changed over twice a day on average. A “traditional” setup time would be at least 45 minutes per changeover – with TubeInspect, this is reduced to 5 minutes.
If we assume a conservative downtime for each machine of £70 per hour, the resulting savings within the first year would be almost £75,000 based on 200 production days per annum.
It is easy to see that even a small facility with limited changeovers can quickly gain massive cost savings, and for larger organisations the savings can be immense. This observation is confirmed by Ralf Unger, quality manager at König Metall GmbH in Gaggenau (Germany), a custom processor of tubes for automotive and mechanical engineering applications that has utilised TubeInspect since December 2006. “With TubeInspect we are in the position to monitor our processes in a fast and effective way as the measuring system shows accuracy information for the bent tubes after only a few seconds. Therefore, the approval for production can now be given in record time. In the past, when the measurement was tactile, we had to wait a long time for the approval. Moreover we have reduced the setup time of our bending machines considerably. The free machine capacities means hard cash to us !”
Reduction of Material Costs
Material prices increase steadily hitting businesses where it hurts, hence the reduction of reject parts becomes more and more important. Thanks to the fast setup of the bending machines, TubeInspect also pays off in this issue. Joe Girtanner, director of production at the Swiss tube manufacturer Serto AG, shares his experiences with TubeInspect: “Since installing the machine, the number of deficient tubes has reduced alarmingly.
During a machine setup or start of a production run, more often than not the second tube meets the requirements, so we do not have to scrap several tubes prior to production. As we mainly manufacture tubes made of expensive materials, we clearly notice the strong decrease of costs in this area. For example, Serto employs the material 1.45.71 (rust-acid-resistant, titanium-stabilized stainless-steel) in order to manufacture tubes for coffee machines. Stainless steels such as this have experienced significant price increases in recent years. Due to the optimized material consumption, Serto can now partially absorb the increased costs during series production”.
Reduction of storage costs
Tube companies traditionally have a high percentage of in-house-manufactured components, with many “active” products at any point in time. This demands a huge need for storage, as every active tube requires a measurement gauge to be available, and sample tubes must be stored in order to be able to cope with follow-up orders quickly. TubeInspect also brings substantial benefits in this area. Not only can the system work as a virtual gauge, measuring all types of manufactured tubes so that you can remove the need for stored gauges, but the system can also calculate the bending data of tubes that come without CAD data.
In this case, the operator uses TubeInspect’s “master measurement” function, automatically generating the bending data and saves them as nominal geometries in TubeInspect’s database for future inspection. Joe Girtanner explains the benefits of master-measurement : “In the past we had to store samples of every manufactured tube, no matter if the batch size comprised 10 or 10,000 pieces. This was necessary to rapidly handle follow-up orders. Today we are in the position to send back the sample tubes to our customers as soon as the data are digitally saved. As a consequence, we have been able to reduce storage requirements immensely.”– and nothing can be more convincing than that !
www.aicon.de
