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Keeping Moulds Running by Design

It is only recently that Carlo Sandon of Whirlpool Italia has begun to talk about the engineering behind an injection nozzle that has already become a standard for the moulds his company uses to make numerous refrigerator components. First, he had to be impressed by the nozzle's performance. His responsibility is keeping Whirlpool's moulds running.

Uptime and Quality

The quest to increase both quality and productivity is intense at Whirlpool, says Sandon. There is no choice in a market as competitive as domestic appliances. Management, therefore, is constantly looking for improvements, and Sandon and his colleagues are particularly pleased when they can improve both quality and productivity together. Incorporating the Pony nozzle from Guzzini Engineering in Whirlpool's moulds has provided benefits in both areas.

Since Sandon is in charge of in-house mould maintenance and repair, his first thought is about uptime, or to be more precise, avoiding downtime caused by a mould. These nozzles, he says, work as his moulds do, around the clock, six days per week. On the quality side, he points to the gate area of a large, flat moulding, noting how the nozzle's precise closing mechanism makes for a smooth, clean surface that needs no postmould treatment.

At the heart of the Guzzini Pony is a straight, large-diameter injection channel that minimizes pressure loss. Always an advantage, reduced pressure loss becomes critical when moulding complicated shapes or flat parts where material must flow long distances from the injection point. Such a description fits most of the shelves, bins and other interior parts of a Whirlpool refrigerator. In addition, since the nozzle's closing pin is activated by compressed air, there is no hydraulic oil present to contaminate the material.

Engineering that Works

Using compressed air to move the piston is what makes it possible to place the piston in a "hot" area, besides eliminating any possible damage from oil. However, that is not the engineering feature of the Pony that Carlo Sandon finds most impressive. It is the construction of the nozzle itself that catches his attention, and the Italian word he uses is "monoblocco." The Pony nozzle is of monoblock construction, compact, sturdy, and with very few moving parts, that is, maintenance parts.

The lack of maintenance and repair is clearly what makes Sandon happiest. He has 40 active moulds under his care, and Whirlpool Italia's refrigerator plant has 24 Sandretto, Negri-Bossi, and BMB machines ranging up to 1,000 tons. The machines are set up in islands around conveyor belt systems and every machine is equipped with a robot from Sytrama or Jrobi to keep the production moving. Despite the continuous operation, there are no more than eight people working in the injection plant. Management, Sandon says matter-of-factly, wants production to continue without a break, and so does he.

The Pony nozzles support this. They come out only during routine maintenance, and the intervals are significantly longer than for other nozzles Whirlpool has used. Sandon declined to give specific numbers, but said the entire reduction in overall maintenance was between 30 and 50 percent, and generally closer to 50. To illustrate why this is so, he takes a small parts storage bin containing the Pony's maintenance components from a rack in the tool room. A few bushings, some resistors for the nozzle's three cartridge heaters, and a few mechanical parts are all one sees in the bin. All together, the parts cost less than US$ 100 and the maintenance time is about 40 to 45 minutes, helped by the nozzle's easy mounting and dismounting. That, says Sandon, is a big improvement over previous nozzles, all of which had more pieces and required far more time.

Entering the Whirlpool Italia complex near Varese, northwest of Milan, you find yourself in a small industrial city spread over many hills. You have to follow the directional signs to the refrigerator factory. Given the product, naturally the factory is a big one, and the injection moulding department occupies a relatively small part of it. Most of the space is taken by large sheet extrusion lines, followed by vacuum and thermoforming systems making liners and housings for the refrigerators. There are the storage racks for those large parts and assembly areas. Other similarly large factories in the complex are making such small appliances as microwave ovens, kitchen ranges, and washing machines. One factory in the complex is unique within all of Whirlpool's vast global operations: a large, well equipped mouldmaking facility.

Angelo Martinelli, who is in charge of mould design in the Whirlpool toolmaking plant, confirms that the Pony nozzle has indeed worked well. He notes that its compact design makes it easy to place. Whirlpool was among the first to try the Pony almost four years ago and the current product is, in fact, the third generation. The earliest versions, he notes, had a few problems, but Guzzini addressed them all quickly. Therefore, the nozzle became a standard, though not for all the moulds that Whirlpool Italia makes, at least not yet.

Besides injection moulds, this facility makes many of the vacuum, thermoforming, and extrusion tools used in Whirlpool plants around the world. Moulds made here are working in China, Argentina, India, the USA, and Brazil, among other places. Part of Martinelli's job is to be sure those tools can be supported on location.

Since Pony nozzles were initially marketed only in Italy, they could not be specified for most of the exported work. That is likely to change. The Pony, which is available in four sizes, is now being marketed and supported in most of Europe, and Guzzini Engineering is in the process of expanding into other markets and broadening its product line.

Contact Information
Guzzini Engineering,
Div. Acrilux SpA
Dott. Andrea Guzzini
S.S. 571-Km 10,983
62019 Recanati
Tel: +39 (071) 75891
Fax: +39 (071) 7574373

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