Sandretto UK & Ireland supply Sandretto machines and automation equipment to numerous manufacturers to assist in the production of plastic and metal parts for industrial castors and wheels. The reliability and flexibility of Sandretto machines is key when products are being manufactured for use with medical equipment.
Click on any of our stories below to read more about how our customers make use of Sandretto machines and equipment:
Tente Limited
IRISH MOULDER SHOWS THE WAY IN HIGH-TECH PRODUCTION
Tente Limited of Ballymote in Co. Sligo, is one of an increasing number of examples of manufacturing success in the Republic of Ireland.
Founded in 1978 to produce plastics and metals parts for the range of industrial castors made by what is now Tente-Rollen GmbH of Wermelskirchen in Germany, the Irish subsidiary has seen substantial growth in its business, particularly over the last few years. To meet production demands, two Sandretto 380 tonne 'Series Eight' machines, recently installed, were followed shortly by two 150 tonne units and a further 380 tonne.
"Not only have these machines given us much needed extra capacity" states General Manager Robert Wallace, "they are providing the flexibility we also need, to produce mouldings for two different product sectors.
"We supply markets worldwide and, consequently, are required to produce high volume, general purpose castor mouldings on the same machinery which must also be capable of moulding the technically more advanced - and usually more difficult - parts, such as castors used on medical equipment."
MOULD TRIALS
Before specifying the new machines, Tente Ireland instituted a series of moulding trials with a three-plate, four-impression tools producing tyres in polyurethane. Capable of providing a challenge for any moulding machine, the tool was successfully trialed - and an SPC analysis also completed - at Sandretto's Rugby factory. The 'Series Eight' screw design proved ideal for processing both polyurethane and nylon.
The machines delivered are equipped with wear-resistant screws and barrels to withstand the wear imposed by the glassfibre and metal fibre reinforced materials used by Tente for its high performance castors.
Other factors influencing the purchase were automatic clamp force control (providing compensation for mould expansion when the clamp force has been set with a cold mould), also stepped injection speed, screw back speed, holding pressure and back pressure.
IMPROVED TECHNICAL AND FINANCIAL PERFORMANCE
During the 1980s the company equipped itself with second-hand machines; only in the 1990s did the programme to install new machines commence. Ballymote is served well by high quality toolmakers in the locality and development of workforce skills had been enhanced through the national F.A.S. training scheme. The technical and production expertise of the 80-strong workforce at Tente is complemented by the addition of the new Sandretto injection machines, thereby leading to a significant and continuing improvement in manufacturing capability and efficiency.
The investment programme included a further five mid-range machines, together with a robot which further automated production. Continuing improvement in its technical and financial performances will enable Tente to continue the expansion of its moulding operation in the near future.
MOULDING TYRES AROUND NYLON HUB
Typical of the more demanding work now going through the Ballymote factory is a series of tools which, depending on the design, either mould nylon 6 centres into previously moulded polyurethane tyres or mould tyres around the nylon hub.
Tente produces a range of castors manufactured to a particularly high specification for demanding applications; typical is the MCS-series twin-wheel castor designed for use on hospital beds. These are moulded in a four impression tool: inserts, in the form of previously moulded polyurethane tyres and the ball races, are placed into the four impressions before the nylon 6 centres are moulded.
At a recent conference to celebrate the 25th anniversary of one of the Group's sales operations, the plastics moulding and manufacturing side of the Tente was explained by Robert Wallace. He used the introduction of state-of-the-art moulding machinery and automation in a presentation which impressed delegates - from the Netherlands, South Africa, the USA, France, Belgium, the UK and Germany - on technical expertise in plastics moulding in the Republic of Ireland.
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Injectaplas
INJECTAPLAS ‘GOES SILENT’ WITH FIVE NEW SANDRETTOs TO BEAT EUROPEAN COMPETITION
In the old Trent Valley railway station at Rugeley in Staffordshire, the family business of Injectaplas is steadily automating the auxiliary operations around five Sandretto injection machines to drive down manufacturing costs, thereby successfully meeting and beating price competition from mainland Europe.
The nine-year old company had already carved a niche for itself as the castor wheel moulding specialist when, two years ago, it embarked on a major capital investment programme. “We realised that we had to take labour out of the work” explains Chris Whelan, now the major shareholder.
“The support we’d had from Sandretto over the years when we’d only bought second-hand machines encouraged us to seek their further advice. Frankly, we’ve never looked back. We now have five machines, all Sandretto, up to 270 tonne, including two of the latest Series NOVE which were delivered this year. Their vastly improved control and reliability mean that we can confidently ‘go silent’ [the Injectaplas term for operating under lights-out conditions]. We’ve become far more competitive with the result that output is continually rising. This year we look like turning over 50% more than last.”
Injectaplas moulds castor wheels and castor wheel assemblies in diameters from 40 mm to 300 mm, and materials as varied as nylon, PBT and regrind polypropylene. Two examples serve to demonstrate how the company is using automation to profitable effect.
Its bread-and-butter line is a 45 mm diameter castor wheel – used primarily for furniture and light commercial applications – moulded from recycled automotive bumpers. When Injectaplas introduced this line they collected the reject mouldings to cut up and re-grind themselves. Using upwards of 5 tonnes per week on this job alone, they now take delivery of pre-ground material in bulk sacks.
AUTOMATED MATERIALS HANDLING TO PARTS COUNTING
These they lift over a bin from where an auger takes the material to a blender for the addition of masterbatch colour, lubricants and in-house regrind, as required. The material then passes to a pre-drier to remove surface moisture and, when nylon is being moulded, a de-humidifier ready for the machine – a 270 tonne - to call off as required.
A conveyor system takes the finished mouldings to the rear of the machine and into polyethylene sacks supported on a carousel. Signalled by the machine, the carousel indexes round after a pre-set number of cycles. “This has proved to be the most accurate, reliable and cost-effective way of counting” says Chris Whelan.
On this job, operator inspection is no longer required. With upper and lower limits set on selected processing parameters on the QC page, the machine responds and compensates and this is proving to be effective and reliable. For example, when a chiller failed, the lock sensor identified that the tool hadn’t closed – expansion due to heat build-up – and stopped the machine. Not a single reject moulding was made.
QC BY MONITORING VISCOSITY
A further example of how information provided by the Sandretto control system is used in quality control is in the moulding of heavy duty nylon castor wheels for a major UK manufacturer. Strength is directly related to polymer viscosity; by having this as one of the QC parameters monitored by the machine control system, together with fill time, cushion final position, hydraulic pressure and average injection, moulding quality is monitored. Every one hundred cycles, the machine automatically prints off the values of these five parameters for the previous 20 cycles; these data sheets are included with the relevant deliveries for the customer to compare current deliveries with those of weeks or even months earlier.
PRICES HELD THROUGH AUTOMATION
Cost savings made through the introduction of automation are passed on to the customer. In six years, Injectaplas has never had to increase the price of the 45 mm diameter castor it moulds from old car bumpers.
From a workforce of ten required when five older injection machines were in use, Injectaplas now employs two people for the night shift, two on days (Chris Whelan includes himself in the day shift) and two senior members of the family.
The aim is to further increase periods of “going silent”. Currently, these periods of unmanned operation between the one shift leaving and the next taking over are little more than an hour during the week and up three hours at weekends. The aim is 8 hours.
Already, with relays wired from a telephone auto-dialer into the machines’ alarm circuits, Chris can be contacted automatically whenever an alarm occurs. “We can only extend automation and, specifically un-manned operation, with machines which are totally reliable. For a small firm, we have taken something of a financial gamble – five new machines, and three in five months! Now, with the means and ability to meet the low-priced competition from Italy and France, we are constantly justifying that gamble.”
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