New flow wrap technology for United Biscuits’ Harlesden factory

Phase III was completed in late 2014 and the company now have six flow wrap lines in place at Harlesden. Food Processing visited the factory to take a closer look.

The Harlesden factory was built in 1902 by Alexander Grant, thanks to its excellent transportation links via the canal and railway. The factory grew from manufacturing two types of biscuit to 387 product lines in the 1930s. By the 1950s, that number was reduced to just four as the start of mass automation arrived at Harlesden. In 2004, the first savoury snack line was installed and then in  2011, the Thames I flow wrap technology line was introduced, followed by Thames II in 2012/2013. 

 

Now, the Harlesden site is 50,000 square metres and operates 24 hours a day. The factory houses 11 lines making over 115,000 tonnes per year, 11 mixers with a throughput of three tonnes per hour and 11 ovens that run to between 70 metres and 90 metres long. On average, the site uses 275 tonnes of flour, 70 tonnes of oil, 55 tonnes of chocolate and 44 tonnes of sugar each day and 35 full trailer loads of finished product leave the site daily. The factory runs two rich tea lines, three savoury snack lines, three digestive lines and three chocolate digestive / HobNob lines, producing 50 million snacks biscuits every day and 24 million sweet biscuits every day.

 

Harlesden is responsible for 40% of United Biscuit’s UK volume input and is the largest biscuit factory in Europe. As such, the decision to move to flow wrap technology for specific product lines started back in 2008 and couldn’t be rushed. “What we were finding was that old equipment was becoming more difficult to maintain and repair,” explains Kevin McGurk, Group Supply Chain Director at United Biscuits. “From a commercial point of view, the old technology limited the number of pack sizes we could achieve. The changeover time from changing pack sizes on the line was excessive with up to four hours of downtime. When you’re producing 2-2.5 tonnes an hour, that’s a significant loss of output. We had a lot of discussions about what technology to use and how to invest money to get the most from new technology.”

 

The company were looking to develop something in collaboration with Bosch and installed a pilot facility in their Manchester site that used flow wrap technology. “Throughput was better, manning was less, efficiencies were higher and it was a successful trial,” says McGurk. “We put together a programme of investment with Bosch to initially focus on investing in flow wrap for the chocolate digestive lines in Harlesden. The commercial team now have much more flexibility to service consumers. Our team have become experts, alongside Bosch, in putting in these new lines and working with them. The latest line was up to full speed within two days of installation. It’s become a standardised technology for our biscuits in that we can use the same technology for each product, increasing our efficiencies and commercial options for the future, so it’s been a successful project all round.”

One of the biggest benefits to the new technology is the easing of the bottleneck in the wrapping area. “This technology runs continuously without stopping,” explains Arthur Lawrence, Manufacturing Manager at United Biscuits. “On one line alone, we’ve increased output from 55 tonnes a day to 70 tonnes a day. The lines work on three legs each, and the advantage is that two legs can take the full output of the line, so all changeovers are done on the run, without stopping the process, saving us four hours each time. We’ve also made considerable savings in terms of waste. The same line that ran at 4.5% waste is now well under 2.5% waste since the upgrade as we’ve saved millimetres on each pack with the new wrapping. Monetarily speaking, it’s worth over a million pounds a year.” In addition, the new technology uses airbeds for the biscuits to slide down before they drop onto the belt. The feed systems are much gentler than the old line. “We’ve made more savings on waste reduction on the digestive rather than the chocolate digestive, probably because the half-coated biscuit is more robust where it’s held together by the chocolate,” says Lawrence. “We were running at around six per cent waste and now it’s around two per cent.”

 

For some of the line installations, the company had to stock build and take production offline for a month, while on others, as there was more space available, the lines could be added without any loss of production. It’s also startlingly peaceful, with only a handful of people needed to run the lines and hardly any noise produced by the lines. 

 

In the oven room, there are 10 direct gas fired radiant ovens and one forced air convection oven. The shells have been in place since the 1950s and 1960s, with the equipment itself upgraded as needed. “As a business, we put a lot of investment into designing new burners about five years ago, making the gas ovens more efficient in terms of gas usage and give the same energy and heat,” says Lawrence. 

 

The ovens run three digestive lines, three chocolate digestive lines, two rich tea lines and three savoury lines. “Digestives are made from a very short dough, almost like shortbread dough,” explains Lawrence. “We use a medium level of heat over 200°C with a relatively long bake time of six to six and a half minutes. The oven is set up to give a lot of heat within the initial zones to produce lift, to bake the product and extract moisture in the middle zones and give it colouration in the end zones. 

“The mini cheddar line bakes for a much shorter time, at a higher temperature of around 300°C and above. We then apply 14% oil including flavouring as a mist which is sprayed onto the product before the cheddars cross over the factory to be packed. Rich tea on the other hand is a shorter bake, at just over five minutes at a temperature between mini cheddars and digestives. The rich tea dough has a lower fat more gluten formation with very elastic dough.”

The Harlesden site is also responsible for chocolate HobNobs. “Made with oats and wholemeal flour, it’s quite a difficult biscuit to control in terms of consistency,” explains Lawrence. Above the ovens is the mixing area, split between bulk and small ingredients. Whey powder, cheese powder, raising agents, sodium bicarbonate and other small ingredients are fed in small batches while the bulk ingredients are transferred over from silos. “We have 11 mixers, all automated,” says Lawrence. “Typical batches vary between 600 – 750 kilograms with a throughput of around three tonnes per hour. Three of our mixers sit on their own load cells so the ingredients are weighed as they’re dropped into the drum, all others pass through a centralised weighing system for the other ingredients. Next year, we’ll be looking into replacing all our silos with purpose built vessels with a view to the future. We want this factory to be a 160 – 170,000 tonne site and we have to invest to do that. Because our lines are becoming more efficient, with less waste, we need bigger silos to meet this increased efficiency.”

Product is then dropped down from the mixing room through a hopper. On the digestive line, the product is cut into small pieces before going through a forcing roller which compresses the dough into the moulding roller, which passes over an extraction web. The product size and shape can be altered depending on the pressure between the two. The product then goes through the ovens. Any excess dough is fed back into the system to minimise waste.

The rich tea dough is initially fed through a three roll sheeter. The dough is then fed through a series of two to one reductions. The product goes through a laminations process, and the resulting layers can be seen when breaking open a rich tea biscuit. Air pockets between the laminations are also developed so that moisture extraction is much easier within the oven. The product then goes through a four to one, then three to one and finally two to one reduction. The product goes through an emboss roller and cutter before it goes through the ovens. Again, any excess dough is fed back through the system.

 

The chocolate digestives are sent from the ovens through a series of shell coolers to bring the temperature down to around 27°C. Chocolate is stored at around 44°C and pumped into a tempering unit. The chocolate is applied at between 30-32°C depending on the enbrober. A bed of chocolate covers the bottom half of the biscuit before it’s cooled. 

 

While the biscuits go through to flow wrap and roll wrap lines, the savoury products cross over the factory to the packing area. The company is proposing to invest in central auto palletisation. The old lines were lifted from Ashby around 10 years ago and allow the savoury products to be hand packed or multipacked. “We rely on agency staff for hand packing,” says Lawrence. “We only need three to four packers for an output of 1.6 tonnes an hour in the larger multipacks. On the automated line, we only need six staff to run the entire primary and secondary packing area for savoury products.”

 

United Biscuits currently exports to 130 countries, with their biggest growth markets identified as Africa, the Middle East and China. “We’ve successfully grown in India already,” explains McGurk. “We invested about five years ago and it’s been incredibly successful, particularly given the heritage of UK products in India. We have manufacturing facilities in India, Saudi Arabia and Nigeria now.”

 

And there’s that small matter of Yildiz Holding acquiring United Biscuits, after months of speculation that had several leading biscuit companies vying for their business. “There’s a lot of synergy with Yildiz that we’re excited about,” says McGurk. “They’re big biscuit producers, but in different markets to those that United Biscuits are strong in. They don’t have huge numbers in the UK, for example, while we’re leading manufacturer in the UK. On the other hand, they have a good market share in Middle Eastern countries. So we’re excited and looking forward to what we can achieve together.”

 

The company is also focused on Lean, which was implemented about seven years ago as a company toolkit for management to utilise as they strove for more efficiency on the line. “We’ve refocused our Lean programme in the past 12 months,” says McGurk. “It was successful as a management tool but now we’re bringing it to the operators who use the equipment so that they know how to use Lean tools and techniques so they can use them to drive efficiency. We’ve recently taken operators from the line to train them via workshops on how get back to basics in assessing and analysing how manufacturing lines operate, where the bottlenecks form, where waste is higher and so forth. Once they understand their production line, then they know how to fix the problem and work with management and consultants on improving waste and lowering bottlenecks and increasing throughput on their lines. It’s been a really successful trial and has upskilled our workforce at the same time.”

 

McGurk believes that food engineers face a combination of issues from skills to efficiencies to developing technology. “For us, if we look at Harlesden specifically, the engineering tasks are changing,” McGurk explains. “We’ve got an ongoing, significant investment in automation. We’ve moved to changeovers on the run, which means that technicians can manage those tasks rather than engineers. Our engineers have had a refocus on preventative maintenance, and bringing their job remit very much back to traditional engineering tasks. Our team is looking at the future to ensure they’re supporting a modernised environment with preventative maintenance. Ultimately, we’re looking to lowering our overheads to make us as competitive as possible, and a big part of that is looking at modernised ways of working across operators, advanced team members, engineers and technicians in order to help drive the company forward.”

 

That drive also helps the company when it comes to the skills shortage that the food and drink industry is facing. “Enhanced automation can be managed better through smaller engineering tasks,” says McGurk. “But there’s still a skills shortage in terms of pure engineering. We have a graduate programme within United Biscuits that goes across the supply chain, and that includes engineering. The programme cycles graduates through different functions of the business depending on their specific requirements and where they’d like to see their careers progressing, and engineering is a large part of that. We’re looking develop both our engineering management capability but also our engineering apprenticeships as well. We work with the College of North West London and we have engineering workshops where students from the college come in and have lectures and practical training onsite.”