Hot air is an indispensable commodity in the industrial arena as it has many applications. Depending on how it is harnessed, hot air is used for more than heating. For instance, it can be used to clean, mould, power, protect, dry, and cure products and components within different manufacturing processes.
Hot air is typically used in most industrial applications for heating, drying, dehydrating, curing, cleaning, sealing, protecting, and preserving. Examples of hot air solutions include centrifugal blowers, autoclaves, furnaces, air knives, thermoforming presses, and heaters.
In this article, we’ll look at how various industries use hot air in their manufacturing processes., We’ll learn the many applications for hot air in the food and beverage industry, aerospace technology, and sectors such as automobile manufacturing, waste transformation, and pest control, amongst others. But first, let’s start with the printing industry.
Printing’s Invisible Assistant: The Hot Air Blower
Centrifugal blowers and heaters are essential components of industrial printing equipment, like offset, gravure, and flexographic printing. Some crucial roles centrifugal blowers and heaters play in industrial printing include toning, drying, and heating. Here are some examples:
Centrifugal Blowers in Printing Applications
Secomak manufactures centrifugal blowers for a variety of applications. Here are some examples of where these blowers are utilised in the printing industry:
Many industrial printers use centrifugal blowers to dry ink that has been freshly applied to a substrate. These blowers provide a controlled environment or blow hot air over newly printed ink. By rapidly drying the ink, printers can prevent smudging and ensure high-quality printing.
Web-based printing processes, such as newspaper printing, use centrifugal blowers in the following ways to maintain accurate and consistent printing:
– Controlling tension,
– Guiding paper or substrate through the press,
– Maintain proper alignment and;
– Prevent the substrate from wrinkling.
Air Knife Systems
Some printing applications use an air knife and centrifugal blower combination. An air knife can remove excess moisture, dust, and debris from the printing substrate – before or after printing.
Some printers – like digital ones – are prone to overheating in certain conditions. Often, printing companies use centrifugal blowers to cool electronic components to an optimal operating temperature.
Heaters in Printing Applications
Heaters also play an essential role in some industrial printing applications. Here are some examples:
Ink Viscosity Control
Ink viscosity is affected by temperature, so it is essential to maintain it at an optimal temperature to achieve consistent print quality. Heating ink reduces viscosity and ensures a smoother flow through the printing press. However, it’s crucial to maintain a precise temperature to prevent the ink from overheating or drying in its cartridge.
Offset printing processes use solvent-based inks that require heat treatment to expedite solvent evaporation. The heat treatment ensures the ink adheres well to the substrate by drying it quickly in a controlled environment.
Printers sometimes use heaters to preheat substrates like paper or plastic before printing. In these cases, preheating the substrate helps to improve ink adhesion and printing quality.
Thermal Transfer Printing
Heaters are used in thermal transfer printing to selectively heat portions of a ribbon, transferring ink onto the substrate. This is commonly used in applications like barcode label printing.
The Sky’s Not the Limit: Aerospace and Hot Air
Aerospace composites are lightweight and high-strength materials commonly used to construct aircraft bodies, wings, and satellite parts. The controlled application of heat is used in two key processes when making composite materials: curing and thermoplastic forming.
Curing of Composite Materials Using Controlled Heat
Two commonly used curing methods of aerospace composites include Out-of-Autoclave (OOA) curing and prepregs.
Autoclaves are traditionally used for curing composites, but more recently, the growing trend is to develop OOA curing processes using controlled heat. Examples include using ovens, heated tooling, or specialised vacuum bags to control temperature and pressure during cooling.
Aerospace composite materials are often impregnated with a resin (called prepregs) before they’re used to create structural components. Prepregs typically contain glass or carbon fibres and a resin matrix. During the curing process, controlled heat helps to bond the fibres and cure the resin. Usually, the components are cured in an autoclave with precisely controlled heat and pressure to ensure proper composite consolidation and curing.
Thermoplastic Forming with Controlled Heat
Some aerospace components are made from thermoplastic composite materials, which are mouldable when heated. Controlled heat is necessary to heat the composites to the perfect moulding temperature without overheating or degrading them.
Below are the different ways controlled heat is used for thermoplastic formation:
- Resin Transfer Moulding (RTM),
- Additive manufacturing (i.e., 3D printing), and
- In repair and maintenance operations for aerospace composites.
The Heat Behind Your Feast: Food & Beverage Production
Hot air is used in many food and beverage production lines and processes. Let’s look briefly at some examples:
Hot Air and Canning
Hot air is typically used in the canning process for the following purposes:
- Sterilisation: Hot air is used to sterilise the containers (jars or cans) and their contents. This helps to destroy harmful microorganisms.
- Sealing: Hot air is used in canning to create a vacuum seal on food-filled containers. Vacuum sealing with hot air helps prevent harmful microorganisms from entering the container and makes the food safe for long-term storage.
Hot Air and Brewing
Some breweries use hot air to produce specialised beer and fermented products. For example, hot air could be used to roast malted grains like barley or other cereals. Hot air is also used for kilning certain types of malt, including Pilsener and pale malt.
Hot Air and Distilling
Distillation is a separation technique that relies on the different boiling points of the components within a mixture. Hot air is used at various stages of the distilling process, depending on the application and the equipment used. Here are some examples where hot air is used in the distilling process:
- For heating the mixture,
- In reboilers,
- In steam distillation,
- In vacuum distillation,
- In rotary evaporators, and
- For drying solvents to leave behind the desired product.
Hot Air and Baking
Hot air is beneficial for industrial and domestic baking and cooking applications for the following reasons:
- Heat transfer: Hot air in an oven transfers to the baking food, leading to various reactions. These reactions depend on the ingredients but usually change the finished product’s colour, flavour, and appearance.
- Even cooking: Well-designed ovens circulate hot air evenly, preventing burning and uneven baking.
- Rising and expansion: Hot air is beneficial when baking products with leavening agents (e.g., yeast or baking powder). The hot air causes the leavening agents to release gas, allowing the dough or batter to rise and aerate.
- Maillard reaction: The Maillard reaction is a phenomenon where proteins and sugars react in the presence of hot air, resulting in browning and improved flavour.
From SIM Cards to Microchips: Precision Drying in Electronics
The process of manufacturing semiconductors like SIM cards and microchips is a complex one. Part of the process includes precision drying components without heat damaging them or introducing contaminants or moisture. Precision drying is essential to ensure the components’ reliability and performance. The drying processes that require warm air or air transfer include:
- Spin drying,
- Vacuum drying, and
- Maintaining the cleanroom environment.
Manufacturing Mastery with Hot Air
Hot air is incredibly versatile and is used in most general manufacturing sectors in one way or another. Here are some practical examples:
Drying and Curing Applications
Hot air is commonly used for drying and curing processes in general manufacturing. When used for drying purposes, it speeds up production time, improves finishes, and helps maintain the integrity of some products.
For example, it is used to dry freshly applied paint or coatings on products, curing adhesives, in kilns, and on calendar rolls for drying materials like ceramics, paper, and textiles.
Heat Shrinking Applications
Heat-shrinkable materials, like some plastics, are used in manufacturing for packaging and insulation. Examples include heat-shrinking plastics around bottles, wires, and other products to provide a tight and protective fit.
When certain types of plastic are heated together until they melt, they fuse together and form a strong bond. This technique is commonly used in the automotive industry for making durable plastic components.
Heat sealing is commonly used in packaging to seal bags and containers. It uses a principle similar to plastic welding, where hot air is used to join thermoplastic materials. However, the plastics used in heat sealing are much thinner and designed to protect contents for transit or storage.
Thermoforming and Heat Forming
Another way that hot air is used in general manufacturing is for shaping and forming thermoplastic materials. Heating certain plastics in moulds and presses makes them malleable and easier to form into specific shapes.
Some manufacturing applications require hot air to create or maintain specific environmental conditions. For instance, some turbines perform more efficiently when their inlet air is heated.
Beyond Warmth: The Utility of Industrial Process Heaters
Specific industries use process heaters to maintain the desired consistency of a particular matter, e.g., warming a liquid to maintain its viscosity and improve its flow for other processes and functions. These heaters circulate hot air inside the storage containers and tanks to heat the contents.
It is primarily thick chemicals that require heating for efficient processing, like petrochemicals, fuel, oil, and nitrogen. Examples of industries that use industrial process heaters include power-generating enterprises and refineries.
Autoclaves, Furnaces, and the Power of 300°C
Equipment such as autoclaves, furnaces, laboratory ovens, and air knives often need heaters that reach 300°C or more, depending on the application. Such high temperatures are usually required in pharmaceutical, biotech, and material manufacturing for testing, annealing, sterilisation, preparation, drying, cleaning, and curing.
However, an issue with high-heat applications is that heat transfer threatens human safety, product quality, and equipment longevity. Thus, air knives and blowers are commonly used to negate the effect of unwanted heat transfer.
Here are some examples of how blowers and air knives are used in high-temperature settings:
Air knives help to dissipate heat in high-temperature environments, e.g., by blowing a continual stream of cool air onto hot surfaces. They are also helpful in regulating the temperature in an environment, and they can improve process efficiency by reducing the need for extended cooldown times between manufacturing steps.
In high-temperature applications like glass manufacturing or metal forging, it becomes more challenging to remove contaminants and debris. Air knives are helpful as they can remove contaminants while maintaining high heat. Additionally, regularly removing debris and contaminants helps to reduce machinery maintenance costs.
High-temperature applications often involve washing, coating, or surface treatments. Air knife systems can quickly and efficiently remove moisture from products, preventing streaks, water spots, or other defects caused by drying at elevated temperatures.
Control and Precision
Air knife systems are customisable to provide the proper airflow and velocity for a specific application. This is essential in high-temperature applications to avoid overcooling or damaging sensitive materials. Air knives that are precisely positioned also help to minimise energy waste while optimising their cooling or cleaning effect.
It is essential for human safety to circulate cool air in high-temperature work environments. Blowers and air knives can help cool the work area and circulate fresh air for those working in such harsh conditions.
Waste Transformation: Dehydration for Biofuel Production
Hot air is revolutionising the way we manage waste and produce fuel. Biofuel is fast becoming a preferred renewable energy source, as so much of it is available. It is made by dehydrating biomass from algae, plants, and animal waste.
Dehydrating garden and animal waste (usually from herbivores such as cows or sheep) for biofuel is an excellent way to reduce landfill pressure. It also offers alternatives for combustion for heating applications.
Beyond Pesticides: The Thermal Pest Control Strategy
Chemically-based pesticides are often toxic to people and may also have carcinogenic properties. While some pest control is best achieved with such poisons, hot air offers a chemical-free alternative. For instance, it can tackle pest issues with targeted heat application without risking human or pet health.
Examples of pest control applications using targeted hot air include killing bed bugs in hotel rooms and killing food moths or roaches during food manufacturing.
Air Curtains: Industrial Efficiency at Doorsteps
Lastly, air curtains are another typical application used in industrial and retail applications. You can see (or rather feel) air curtains at some shops and climate-controlled environments, like air-conditioned factories. They are usually installed at the entrance or exit of a climate-controlled area, like freezers, chillers, ovens, or air-conditioned buildings.
The invisible curtain of air (usually blowing downwards) provides a barrier that causes conditioned air to reflect back to its environment. As such, air curtains can vastly improve energy efficiency in environments where doors are impractical.
As you can see, hot air is helpful for many industrial applications. Some industries covered in this article included the printing, food and beverage, technology, manufacturing, and renewable energy industries. However, there are far more applications for this humble commodity.
Secomak delivers top-tier hot air solutions for most applications. We can help to tailor your industrial hot air needs and maximise your company’s production and efficiency. Read our case studies to learn how we’ve solved industry leaders’ production and manufacturing woes with hot air.