Computer optimisation of moulding turns costs to profits.
Despite the success of experience, there were many delays and unforeseen production problems in Arad's design and moulding process. The company recognised that to continue as it was was unacceptable and investigated the benefits of using a computerised analysis and optimisation process - Autodesk Moldflow. Arad has now accepted the technology and embraced the benefits that come along with it.
Arad has been moulding for many years and has more than 700 active moulds, building 70-100 every year with 25 mould makers. According to Nick White: "In plastic moulding, many unproductive processes are accepted and tolerated. In our industry many businesses accept the long time lines for tooling, the many tool trials, the late stage tool modifications, the unpredicted long cycle times, the dimensional problems like warpage, voids, sink mark issues, and the list goes on. At Arad, if we were to continue to develop quality solutions at a profit then we could not accept these problems so we took a serious look at how we could improve our overall process."
The Autodesk Moldflow analysis suite was identified as a tool that could aid in this process improvement initiative. The company deployed the technology and now applies Moldflow optimisation at every stage of development: R&D, engineering, and manufacturing.
Mr White comments: "We don't use Moldflow to identify problems in production. We use Moldflow to fully optimise our designs as soon as they reach a set milestone in our process. The key word here is optimise. Our engineering team looks for areas on each design to cut cost. Moldflow is used to look at many design iterations to achieve this. Before Moldflow we designed good parts. Today we design the best possible parts, resulting in significant savings in material content and time.
"Traditionally we would go through a prototype tooling phase. This step has been replaced by our Moldflow virtual desktop tool trial process. This enables us to anticipate any potential manufacturing problems early in the process before committing to tooling. By optimising our designs early, significant savings are delivered at the tail end of the process. Our scrap rate has been reduced to well within our targets and cycle times are the quickest they have ever been. The enhanced throughput on production enables Arad to produce more parts annually and ensures we protect and grow our profits."
"Our engineering resources are not fire-fighting late stage design changes caused by poorly designed parts. This now allows our engineers to focus on what they are paid to do, develop products, which for us is revenue-generating activity."
MASS REDUCTION OF A MEASURING CHAMBER
One of the first parts optimised under the new regime was a measuring chamber. This part is a fundamental element of a water meter and one of its most important.
The original weight of the measuring chamber was 46 grams and the moulding ran at a cycle time of 40 seconds. It had a cold feed, direct sprue that needed to be removed by machining after moulding. The mould was a single cavity tool due to the incapability to produce more than one cavity within the required tolerances. Therefore, the maximum annual run which the mould could produce was 420,000 parts. This was not enough to withstand the growing demand for the product. By using Moldflow on the next generation design Arad optimised both the part and the mould designs, validated all iterations, and eventually produced a two-cavity mould.
Moldflow also allowed Arad to try all potential gating scenarios, which the engineering team has found to be the best way to reassure management of the educated and informed decision being taken. Nick White explains: "Traditionally, we could not have validated this until it was up on the press. We looked at all options and decided on the best design as there are always compromises between quality, cycle time, dimensional accuracy, and materials selection. It really works, you see it on the screen, inject it on the mould, and it is the same.
"The resultant savings were unbelievable. We reduced the weight to 30 grams, resulting in a 28 second cycle time. On this one design alone it saved 16 grams in material for each part. This means an annual saving of 9-6 tonnes of material. This optimisation study now allowed us to manufacture more in the same amount of time, raising annual production to 600,000."
METAL-TO-PLASTIC CONVERSION OF A FLOW TUBE
Arad's biggest market place is the United States, with 80 per cent of its products being exported there, This market is very competitive and the US market place is very conservative and favours the traditional feel of metal solutions. A lot of Arad's products are historically made from brass or bronze. With the rising costs of these metals it is becoming more common to replace metals with plastics. Arad's plastic products cost less but still meet the performance requirements set by international standards. This saving is passed on to the company's customers, and then on to the end user.
One metal replacement task was a flow tube where Arad was requested to replace the bronze part with a plastic one. The design of the flow tube needed to be optimised so its design-for-manufacturing feasibility was validated in Moldflow.
Even though Moldflow predicted the best gate location at one end, Arad continued to look at all scenarios; the software enables informed decisions to be made within a balance of all criteria. With this part it is critical that both openings are in line within a set tolerance. If they are out of tolerance then it can lead to a poor fitting when connecting to the in-line piping installation and this can result in water leaks. When gating from one end an unacceptable amount of warpage was occurring. Having reviewed all gate locations, Arad decided on a centre gate. The flow of the material is not as good but the deflection is within tolerance.
The result proposed by Moldflow was therefore a compromise between the flow of material, the deflection of the part, and the gate location. One of the key benefits of flow simulation is that optimised designs offer a wider processing window inside which good parts are produced and the size of this window can be viewed. Moldflow can deliver the best processing settings inside this window so that when material and processing variation occurs good parts are always produced, providing stable production. Alternative grades of materials can be compared to see which will deliver the lowest cost part. These tools have enabled Arad to introduce this new virtual tool trial stage early in the development process.
Arad produces 30,000 of these components a month. Going from metal to plastic saved 70 per cent in cost. The mould cost $30,000 so Arad saw a return in one month of production. This new design was accepted by the US market dependent on NSF61 approval (a standard for drinking water in the USA by FDA). With a happy US marketplace Arad has branched out and now sells this product to the rest of the world as well.
VALIDATING TOOLMAKERS DESIGNS
As with many businesses worldwide, Arad uses mouldmakers in China. Even though it is the mouldmaker's responsibility to ensure the mould delivers quality parts, Arad takes ownership of gate position and validates toolmakers' proposals early in the design process. Nick White explains: "Even though we outsource some toolmaking to China, Moldflow allows Arad to minimise risk and increase confidence in being right the first time and at the first tool trial."
Arad reckons Moldflow is saving it 20 -30 per cent in mould manufacturing costs. "This in itself justifies the investment in Moldflow, but the key benefit to Arad is the reduced time-to-market. On average our moulds take 500 hours and we feel we are now saving around 100 hours by using Moldflow. Based on an in-house hourly rate of $20, this equates to a saving of $2,000 per mould."
Arad could have outsourced Moldflow analysis to external consultants, but decided that it would benefit directly and could develop its own internal consultants. This protects the intellectual property in its products and also in their design-for-manufacture.
So what is next for Arad? "We are getting even better at optimisation now", says Nick White. "Arad continues to grow and is now the 5th largest water meter provider in the world and the number 1 provider in Israel, but we are not complacent about this. We are always seeking new ways to improve and innovate.
"Moldflow is like the mobile phone or the internet. I could not imagine working at Arad without Moldflow now. How did we manage before Moldflow? We take these technologies all for granted today but we somehow managed to operate before they existed. We have a much more productive and easier life now."
Arad specialises in the design, development and manufacture of water meters for applications such as domestic, waterworks, irrigation, and water management throughout the world. The company was founded in 1941, and has built a worldwide reputation in measuring, reading, collecting, and managing data from water metering to billing systems. In 2004 it became a public company and is now traded on the Tel-Aviv stock exchange.
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|Title Annotation:||designing with engineering materials|
|Comment:||Computer optimisation of moulding turns costs to profits.(designing with engineering materials)|
|Publication:||British Plastics & Rubber|
|Date:||Feb 1, 2011|
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