In the early sixties hardly anybody knew how heat sealing machines work. For those of you that were born in or before the sixties, you may remember your lunch choice being made through a glass shelf on a café counter top, where the selection on offer was a bland cheese or ham roll, stuffed into an equally bland white paper bag. Any sandwich was likely to be left growing stale as the corners turned up in sympathetic disdain.

So, how did we go from this scenario, to the modern range of near exotic sandwich and lunch on the go delights which now tempt our palate and purse? Approximately 11.5 billion sandwiches are now consumed in the UK alone every year, creating an £8 bn a year UK industry with the most developed sandwich industry in Europe – all achieved since the 1980s.

As we’ve been enticed by the salivating selection of sandwiches and fillings in the food to go section, this transformation has gone hand in hand with a change in both our working and social lives. Now, we often don’t leave our desks for lunch or sit down to eat, while racing round the shops like a whirling dervish. Food to go has fitted perfectly into our modern, busy lives, and the food to go industry has responded superbly to our consumer and lifestyle changes.

With the increased demand and expectation of a high-quality food to go product, still increasing by the rate of 80 million sandwiches a year, an industry has emerged to fulfil our ever-increasing appetite with enhanced production rates and packaging which has come a long way since the white paper bag.

As the consumer demands more fresh products, it also drives environmental concerns.  In response, heat sealing technology has enabled high speed, rapid sealing of sandwiches and food to go products, which can incorporate the latest environmental packaging and delivers improved presentation.

From the rise of the artisan producer to the now ubiquitous ready meal, with the advent of heat-sealing technology, any producer, large or small can heat seal their product to deliver fresh quality food to their customer.

So, what exactly is Heat Sealing Technology? Let me explain how heat sealing machines work. It is a method of sealing packaging using a heat sensitive, stable adhesive, which will not contaminate the product. By applying heat and pressure on the adhesive area, this can result in an air tight sealed pack, without tainting or contaminating the food product inside. It is also tamper evident, providing added security.  An array of different heat seal packs have been developed to suit a multitude of products.

Heat Sealing is a technology which is able to incorporate the latest biodegradable and compostable packaging, ensuring a tamper proof pack, increased protection against contamination and the application of labels, dispensing with the need for secondary labelling, saving both labour and material costs. This is now standard in the food industry for sandwiches, food to go and ready meals.

Sealing time and temperature range is guided largely by the type of seal film and cardboard manufacturers recommendation. There is an optimum range that the film and cardboard will seal at, consequently heat sealer machines have a digital temperature control which can be adjusted to suit the film and packaging being sealed. With regards the seal time, this is generally in seconds which may be estimated by the operator on smaller hand sealers, or in the case of semi-automatic and fully linear automatic sealers, timings are incorporated into their design.

A good temperature distribution of the pack is achieved by using a relatively large, thick metal plate, which is highly conductive, while the heat is maintained at a very stable temperature. Modern digital temperature controllers have sophisticated algorithms, known as PID, that vary the supplied heat from the heater element to ensure thermal stability. It is important that the heater sealing plate is presented level to the film or pack. Now you know how heat sealing machines work.

General factors determining the strength of a seal are affected by the properties of the adhesive and amount used per square metre applied to a film. In the case of cardboard packaging, modern cardboard films are laminated to a cardboard outer pack. This requires a relatively low temperature to provide a strong seal.

Typical mistakes which arise in packs which are heat sealed is the user not abiding by the manufacturers’ recommended seal time and temperature. Badly maintained equipment will also deliver poor results with inconsistent sealing. If equipment is not cleaned properly, allowing food to remain or fall onto the seal area, while the support gaskets remain worn or damaged, this will result in a poor seal and increase the risk of contamination of the product. While cost is always a factor for businesses, saving money with poor quality, unregulated, sub-standard packaging, not to regulated quality standards can cost business’s with poor product presentation and resulting in an increased risk of health issues.

The advent of heat seal technology across the packaging industry, enables those producers needing to seal just a few products a day, can present their food with equal flair and quality as those producing for high end outlets and chains making them even more competitive. Single heat sealers are available which can seal one product at a time – ideal for those requiring a handful of select products a day. For those who need to seal in higher volumes, without an increase in staffing, sealers have been designed to accommodate this. Semi-automatic models, save time, effort and staffing, while delivering a final product which is both professional and appealing to customers. The exponential rise in sandwich consumption has required the development of super-fast sealers with the ability to seal approximately 3000 packs an hour, using the minimum of labour and delivering exceptional results.

Proper advice and support are key factors when it comes to creating proper heat seals, as there is a strong interaction between the material used, the machine engineering details and the machine settings. Soken Engineering, specialists in heat seal technology for over 40 years’, have responded to the ever-evolving demands of both consumer and business alike. Consequently, they’ve designed and manufactured a range of quality heat sealers to accommodate all level of producers. For an overview of their models and further information see: