Drive helps improve mixing capabilities for biscuit manufacturer
09 October 2012
A UK-based biscuit manufacturer has succeeded in improving the quality of its products and potentially reducing the amount of wastage caused by the use of aging slip-ring motors. It has also improved its ability to develop new products, following the installation of a new drive on one of its dough mixers.
Initially, the company was interested in investigating the potential for saving energy on its ten dough mixers, each of which is driven by an 18.5 kW slip-ring motor. ABB Drives Alliance member Halcyon Drives was asked to investigate the benefits to the application and any energy savings through the use of an ABB induction motor, driven by an ABB standard drive and comparing this against one of the slip-ring motor driven mixers.
Paul Mayman, area engineering manager for Fox’s Biscuits, said: “Although the initial reason for the project was energy saving, it soon became clear that the drive gives us a lot of other advantages that were more important to us. One of the major ones is the flexibility to run at different speeds than previously. We have a lot of other ingredients in our biscuits, such as fruit. Previously, the mixers might overmix, leading to staining where the fruit becomes a mush rather than remaining whole. This helps us maintain a high quality product and avoids the situation where a whole 400 kg batch of dough could be wasted.”
The ability of the drive to change the speed of the mixer also allows the company to be more innovative. “With the drive controlled mixer, we can experiment by using different speeds throughout the mix, from as low as two rpm to 50 or 60 rpm, depending on the recipe.”
The greater torque of the ABB motor is also said to leads to higher mixer reliability. Previously, if the company was trying a dough that was harder than that used in their usual products, the old slip-ring motors would not have the torque to turn the mixing paddles and the motor would trip out. Using the new motor means that the maintenance engineers spend less time on them and the production department has more confidence that the mixer will perform correctly as required and less production time will be lost.
Mayman continued: “The drive also gives us a lot of other facilities, such as the load analyser, which saves process data such as current and torque values that we could use to assess production issues. Although we are not using these facilities as yet, they are another example of the flexibility of the drive and could become more important in the future.”
Following the installation of this drive and motor on one of the mixers, Halcyon discovered that the power requirements on both mixers were significantly less than rated power, indicating that the slip-ring motors were greatly oversized.
The mixers typically run 24 hours a day, seven days a week, with a duty of around 10 minutes operating time every 30 minutes. In addition to the process quality improvements, the ABB standard drive gave a cut in energy use of 30 percent, producing further savings on the already low running costs. As well as the drive on the existing mixer, Fox’s intends to convert the remaining nine mixers to drive control.
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