What is the Principle Behind an Airshaft? Understand its Basic Functionings and Applications



1. Basic Principles of an Air shaft

An airshaft (or air expanding shaft) works by pumping its internal air shaft bladder which pushes out the external gripping teeth/panel/rubber to hold onto the materials from their core. By releasing the air, the gripping medium un-grips the materials, allowing easy replacement. 

In other words, an airshaft expands or compresses to hold or release web-fed materials. 


Figures: Black circles (left) and orange circle (right) indicate the expansion of internal airshaft bladder.

2. Airshaft Names and Applications

1. In roll-to-roll manufacturing processes, the essential component of handling winding reels is the airshaft.

Imagine the kitchen rolls or cling wraps common in a home kitchen, their manufacturing processes were all carried out with winding reels. This is also known as a Roll-to-Roll or Reel-to-Reel systems.

During winding or un-winding, airshafts' gripper (e.g. teeth, panel or rubber) can firmly hold onto the inside wall of the material core. Not only does this allow easy replacement of web-fed materials, its firm grip also allows fine control over winding speed and torque (must pair with motor, brake clutch or control systems etc.)

To achieve high-stability winding/un-winding, it relies not only on the drive system (i.e. airshaft), but also the tension control and winding accuracy. This is done by pairing with Minply's other systems, such as tension control system and alignment system

Therefore for any flexible materials, airshaft is the ideal component for the winding process. Materials include but not limited to, flexible PCB, packaging, printing, papermaking, battery, medicine, semi-conductor, optical film and copper/aluminium film. 

2. Airshaft is also known as air expanding shaft, which describes itself pretty well.

The usage of airshafts has been in the winding industry for many years, where Minply has been serving for 30 years. 

Our airshafts are custom products, and we often name them in the sequence of [Material] [Type] [Standard / Reinforced / Super-reinforced] airshaft.

📝 For example

The name is [Steel Lug Super-reinforced Airshaft], meaning this product is a steel made super-reinforced airshaft which uses lugs as the gripping medium.

The 'super-reinforced' here indicates structural reinforcement, and is selected depending on client-provided information such as size, material and application. Therefore, the information provided is crucial during the initial design phase in order to produce the correct outcome.

3. Airshaft Structure

Our airshafts are custom products and are made specifically in type and size by evaluating customer-provided data. This can result in a more convenient, efficient and durable solution. 


The image above is an example of Aluminium Lug Airshaft. From its sectional view, we can see that an airshaft mainly consists of axle (a.k.a. body or wheel surface), rubber air tubes, air nozzle, teeth, spring, axle core and countersunk screws etc. After pumping air through the air nozzle, the air tubes inside will inflate and push the teeth out to grip onto material core.

Hence, the frequent expanding and releasing of air tubes means an airshaft's lifespan depends on its usage and the pressure applied. 

Since air tubes are comsumables, for any operating problems, please see "Airshaft Not Working? Six FAQ!"

📝 Other common airshaft specifications :

  • Axle material : Aluminium Alloy / Steel / Carbon Fibre / Additional PE Wrap
  • Core material : S45C / SCM440
  • Grip type : Teeth / Panel / Rubber Stripes / Rubber Teeth / Key Bar
  • Other winding supports : Addition of Bearings / Balls to wheel surface

4. How to Start Customising a Suitable Airshaft?

Since it is customised, the clearer your request, the better your airshaft will be. 

Feel free to read the FAQ underneath, or go to "5. What Information Should I Provide When Querying?" further down. 

1. Your inflation method

  • Do you inflate airshafts using air pump paired with a nozzle? What kind of nozzle?

        ➠ Minply provides various nozzle for air pumps, mainly : Japanese nozzle / Japanese pointed nozzle / Schrader valve

  • Do you wish to auto inflate your airshafts?

        ➠ We can create tapped holes depending on your specification, and by pairing with a rotary joint and a solenoid valve, you can skip manual inflation - making the machine more autonomous. 

        ➠ Typically a PT thread hole is tapped at the core, to allow rotary joint to connect and pump air (see figure below).

2. Your web's core material - type choices for your airshaft

  • What is your web's core material? Plastic, steel tube, glass tube, paper tube?
  • What is the diameter of this core/tube (mm)? Common diameres are 3" or 6", which equates to 73~77mm. Therefore, please provide an accurate measurement in millimetre so we can evaluate the best size for your application.

3. Ambient environment

  • To be operated under normal atmosphere? Or vacuumed space?
  • Any acidic or alkaline gas in the air?
  • Other environment requirements?

4. Machine and web material characteristic - airshaft material and structure design

  • What is the speed and the max diameter after fully winded?
  • What is the web material? What is the weight when fully winded (max diameter)?
  • Winding from the centre or from a surface?
  • The range of tension?

5. Other requirements - such as fixation method

  • To pair with a machine's drive system, please provide us an engineering drawing of your machine.
  • To simplify the replacing process on double fixation airshafts : safety chuck.
  • To simplify the replacing process on single-arm airshafts: disc fixation (core and axle separated, jointed by a disc).

5. What Information Should I Provide When Querying?

If all the questions above seem overwhelming, try taking a look at our standard airshafts first.

Please answer the following essential questions, and let Minply design for you!


Airshaft Enquiry Procedures:

    1. Please provide material requirement, ambient environment and machine width etc.; and if available, engineering drawings
    2. Our company will design the most suitable airshaft according to the requirement you provided.
    3. Provide drawings and quotation

    Want to know more about roll-to-roll? Start from the essential component - airshafts!
    If you have technical or quoting problems, please contact us.

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