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Customised bearings for hygiene-sensitive applications

Plain and linear bearings from igus® in multihead weighers

With the support of igus®, Multipond, a world-renowned specialist for fully automated multihead weighers, can standardise the used bearing materials. In addition, igus® has developed a customised linear bearing housing for Multipond that meets the high requirements of the food industry in terms of design.
When every gram counts, numerous food manufacturers rely on the automated multihead weighers of the Atoma GmbH in the Bavarian Waldkraiburg, which distributes its systems under the brand name Multipond.

Multihead weigher

The multihead weighing systems from Multipond are in use worldwide - primarily in the food industry.

 
Drop mechanism

The drop mechanism of the containers - which some users clean in the washing machine - is equipped with iglidur® plain bearings.

 

High-precision, fully automated weighing systems

The company has a very good reputation in this highly specialised market. The weighing systems work precisely and prove their worth by achieving the accurate fill weight each time. The high-precision load cells with readings recorders from own production contribute towards this purpose, along with the so-called selective combination principle: the products are first supplied to the individual weighing systems, then to a storage container. A computer determines the combination which comes closest to the target weight. Since the systems are equipped with up to 36 individual load cells and containers, this principle was found remarkable even in foodstuffs such as cereals, where several ingredients are filled in a prescribed mixing ratio.

Feeding unit

The feeding units are individually constructed and adapted to the packaging machine.

 
Feeding equipment

The lower part of feeding equipment - the lowering screen - rises and falls in the fast cycle of the thermoforming machine.

 

Multipond weighers are quick: the most powerful systems with 36 heads provide more than 500 wpm. They are made in Germany with high vertical integration, are usually integrated directly into the fully automated production line, and they are in demand worldwide: Multipond has already made more than 3,300 systems. The latest models are equipped with the unique automatic calibration, and besides the weighing, the plants master the functions of dosing and counting.

Good experience with iglidur® bearings

The current trends also include a stronger consideration of the hygienic design, besides the ever increasing performance and accuracy. Martin Sedlmeier, group manager for commissioned design: "The weighing systems come into direct contact with the product and are arranged directly above the packaging machines. Therefore, the components must be lubrication-free. “
 
This is one of the reasons why the drop mechanism of the containers is equipped with iglidur® plain bearings. The lubricant incorporated in the slidable high-performance polymer is not released into the environment. In addition, the plastic plain bearings are insensitive to the very thorough cleaning processes in food production. In addition to hot steam and high pressure, aggressive media are also used here - and the weighing containers are put into the washing machine by many users.

Development goal: One (iglidur®) material for all (hygiene) applications

The Multipond engineers use plain bearings made of different iglidur® materials. Sedlmeier: "There are three parameters for the selection of materials: the temperature range, the electrical conductivity and the hygiene or FDA requirements. Depending on which of these parameters is in the foreground, we use another material from the iglidur® product range. “
 
In the future the selection will be even easier. Because, together with Multipond, the igus® specialists have developed a new iglidur® material that covers all three properties and can therefore be used universally. This material is currently undergoing the final tests in the laboratories in Cologne. When it is approved, Multipond can reduce the type diversity of bearings to one-third.

Case study: linear technology for transfer system

Increasingly, Multipond has been offering customers not only customised weighing systems, but also the conveyor systems including peripherals for the integration of the weighing systems into the entire production plant. An exemplary plant is being set up in the production halls of the company. Martin Sedlmeier: "For this customer, we configured a 36-head weigher with a transfer system that combines different cereals with a portion weight of 10 to 20 grams according to the recipe. Each of the 18 outlets, which can be filled at the same time, has a capacity of 30 drops per minute. " Thus, the plant can weigh 540 portions per minute.

Faster cycle, short stroke and high forces

Multipond system

The lowering screen is guided via a drylin® linear guide with RGAS housing.

 

The entire complex is located directly above the thermoforming machine, which produces and supplies the trays. The lower part of Multipond system, the so-called lowering screen, rises and falls at high cycle rate and with 40 millimetres stroke above the packaging machine and ensures the quick and precise filling of each packaging unit.
 
Since the lowering screen is fixed only on one side, high forces including tilting moments act on the linear bearing, which originates from the drylin® R product range from igus®. The housings of the type RGAS allow an exact and wear-free shaft guidance via the proven iglidur® liners.

Here, too, there is a current development project: igus® has used a special type of RGAS linear housing for Multipond, which - apart from the usual sliding elements - is entirely made of stainless steel. The end pieces of the shafts are also made of stainless steel. Thus Multipond achieved an enhanced corrosion resistance in the frequent and thorough cleaning operations, to which such machines are subjected.

Atoma and igus®

Martin Sedlmeier, Custom Design group manager at Multipond (right) with igus® sales consultant Thomas Weber.

 

Detailed exchange: What do the users need?

Both projects - the new, universal and hygienic iglidur® material and the solid stainless steel housing - were developed in a joint discussion between the Multipond developers and the igus® sales consultant Thomas Weber. Andreas Peters, New Design group manager at Multipond: "The question 'What do you need?' is really serious meant at igus® and new solutions that we can test are developed based on our answers. In our view, this is quite unique in our industry. “

Here, you can find the products used
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