Project 
Cake Manufacturing Line – Efficiency & Waste improvement
Background
B&N Europe was asked by a major manufacturer of leading brand and own-brand cakes to train and coach the site team in their largest factory. The product made on this line was a layered cake, two lanes of sponge where deposited and baked through a continuous oven and cooler. The top crust of the sponge was then trimmed and removed, and then cut into strips as it passed through cutting rollers. A layer of jam was added and the strips of sponge were manipulated over one another using mechanical ‘ploughs’, guides and up and over belts to assemble 8 lanes of cake. The cake was cut into individual lengths, wrapped and packed. This was a high volume, high efficiency line with genuine daily efficiencies in the mid 90% range.
Issue/Problem
Although the line was very efficient, waste was inherently high as a result of the need to trim the top crust off the sponge. This was seen as necessary waste and was not considered a problem that needed to be improved. However, top crust waste was by far the biggest source of waste in the plant, amounting to over 10 tonnes of waste per week. In addition, the ‘make-up’ area, where the sponge was mechanically manipulated to form the cake, frequently suffered from pile ups and required 3 operators to clear them quickly. Even so, every pile up produced 20-30kg of cake waste. The team had identified that there was an opportunity to speed the line up, but the working conditions for the operators in the make up area was such that this was not practical, and any increase in speed would simply have just produced more waste.
Solution 
Although the top crust waste could not be completely eliminated, the team found that the variable which dictated the quantity of top crust waste produced was sponge height. There was a minimum sponge height required to meet the weight and size specifications of the final product, set by the height of the top crust trim knife. However, there was variation in baked sponge height across both the width and length of the lanes of baked sponge. Dealing with this could lead to a reduction in sponge height – the trimmed height would not change but less would be trimmed off. The team used PCS to identify 5 root causes responsible for variation in baked sponge height. The main root cause was the deposited batter profile going into the oven. Like most baked products the sponge rises more in the middle of the sponge, so by compensating for this in the batter profile the team were able to create a flat sponge coming out of the oven. This enabled the total height of the sponge to be reduced, reducing top crust waste significantly. The team also used PCS on the make-up waste issue, finding 4 root causes that caused the cake to pile up as it was being assembled. These included the radii of the bends that the sponge travelled over, which was splitting the sponge, and also a very slight discrepancy in belt speeds -which wasn’t noticeable to the naked eye.
Benefits
- By reducing the sponge height, 14% less batter was required to make the same quantity of cake, this was a £200,000 pa reduction in material costs
- The Make Up waste was reduced by 70%. This improved working conditions in the area significantly and the 3 operators could be reduced to 2.
- The improvement in the working conditions also allowed the line speed to be increased by 3.5%.
- The reduction in waste and the speed increase led to a total increase of 5.5% in line efficiency, freeing up capacity to make a further £315,000 RSV of product
