CNC Engineering Case Studies
Washing parts may be considered a secondary operation to the real business of cutting metal in manufacturing, but for a company that produces around seven million parts per year, cleaning and dispatching those components in a condition expected by customers can become a major headache.
This was the situation at Hertford-based Quailiturn. With its inventory of high production CNC sliding head and twin turret fixed head lathes and milling machines, the company was having no trouble keeping up with its required production rates, but washing all those components was beginning to create a backlog in production which was having an adverse impact on the business.
Increasing the company’s washing capacity became a priority for the company’s managing director Nick Groom. Qualiturn already had aqueous washing systems (mainly used for its mild steel parts) but its old solvent applied washing system was in urgent need of replacement.
“Our old perchloroethylene machine worked well but the throughput compared to the rate parts were coming off our lathes was just not keeping up,” Mr Groom explains. “There are also situations in-process that benefit from quick washing. For example, when you want to get parts through inspection as quickly as possible to avoid any scrappage, particularly for large batches.”
Cleaning parts is not just a question of making surfaces look good. Often washing is required because of additional processes that a component will undergo once it has been machined. Dirt and contamination from cutting oils, coolants, swarf and other particles produced during the cutting process can affect subsequent plating, coating, welding, bonding, and assembly.
Because of the wide range of turned parts and batch sizes that Qualiturn produces it needed a washing system that could be as flexible as possible and easy to programme for all the different washing cycles that might be required.
The company opted for a German built, Pero R1 washing system supplied in the UK by Kumi Solutions.
“The Pero machine is able to do many different types of washing programme,” Mr Groom continues. “You can do a static wash, a rotating wash, balance wash or tilt wash at any angle, for example, if you have hole in a part which you want to ensure gets a good flush through with a jet. Essentially you can customise a programme for any type of part. The quicker cycles also mean that we can deliver quicker. We are often in the situation where we do a machine set-up one day, make the part, wash it and then deliver it the next day.”
The Pero R1 machine also carries out ultrasonic cleaning as well as rinsing, final wash and drying. An automatic shut down and start up function also helps to save energy.
Qualiturn produces a wide range of parts from a broad range of metals. In its thirty year history it has supplied parts to virtually every industrial sector.
“As a subcontractor, we have so many different parts and contracts and that means washing and handling can be very varied too. Parts may have blind holes or through holes, there may be hundreds of parts in a basket or just one. Some of our baskets have dividers to avoid metal to metal contact to prevent problems such as damage to threads. This was why it was so important to have a machine that was easy to operate and programme.”
With each new job a new cleaning procedure is created but Mr Groom says once it has been established it is very easy to repeat when it is needed.
Qualiturn has opted to use Dowclene 1601 from Safechem as the main washing solvent with its Pero R1 machine. The chemical is a modified alcohol (alkoxy propanol) that has established itself as an environmentally safer alternative to Trichloroethylene and Perchloroethylene solvents that are said to carry some carcinogenic risk.
Fire hazards or risks to operators are minimised by the fact that the washing fluid is applied and the dirt and contaminants removed in a closed loop system.
The rate at which cleaning fluid is used by the machine is reduced thanks to its continual distillation unit. This means the cleaning chemical is re-used after being heated and condensed to separate it from the oil and other containments washed off the parts. The waste oil and dirt is then discarded.
Safety features were an important consideration when Mr Groom was looking for a new machine.
“It has many good safety features. It cleans its own filters and lets you know when they need to be changed. We wanted to avoid any accidents like lids coming off the baskets. If a part does manage to make its way out of a basket it will shut down automatically and it warns you if there is an issue with the cleaning solvent.”
Like cutting oils and coolants the condition of washing fluid has to be monitored to avoid any problems.
“After a while the solvent can become acidic and it can start to damage the machine, so you have to regularly test it. Our operators went on a chemical training course by Safechem so they can recognise any tell-tale signs and carry out the monitoring of the fluid,” Mr Groom says.
Qualiturn uses filters on the machine down to 10µm but even finer filter sizes are available if required. Mr Groom says a balance has to be struck between cleaning a part and making it vulnerable to oxidisation and corrosion. One option is to apply temporary corrosion inhibitor during the washing cycle, particularly if corrosive susceptible parts have to be shipped long distances.
Before the machine was delivered to Qualiturn, Mr Groom went to Germany to see it in operation and sign it off.
“Like us, Pero is a family firm. They have invested a lot in their factory and it was good to see they how long-established they are. I could see that we would have no problems getting parts or support longer term.”
Qualiturn is due to move premises to a larger single industrial unit in 2019, so Mr Groom wanted to be sure that the Pero machine would be future proofed and able to add additional equipment such as longer conveyors and more automation to help smooth production.
“You can add bar code recognition for faster identification and programming of the baskets, robots for loading and unloading and additional dryers for cooling. We will be looking at all those options in the future. As long as the maintenance is carried out it should last us for many years. There are other Pero machines in the UK that are up to 20-year-old and still performing well, which shows how reliable they are.”
Investing in washing systems can be costly but Mr Groom is convinced it is the right move for Qualiturn.
“It has been the best equipment purchase that we made in 2016. An extra turning machine can get lost in the crowd, but with this machine you can really see the affect that it has had on our throughput. Any backlog of work that we previously may have had has gone.
“Washing can be a problem. You make great looking parts, which you take a lot of care to produce, and all that can be easily ruined by your washing process, or when handling or boxing up.
“Cleaning is important and it’s something that we want to be better at than our competitors. If customers receive dirty parts it does have an impact, regardless of any other aspects of the engineering. It’s all about adding value to what you produce.”