Involute vs Orbital Blades
Eben van Tonder
26 July 2023

Introduction

High-speed slicers have involute blades, but some have orbital blades. What is the difference and what is the function of the involute design? Where does the concept of an involute come from and how did it end up in meat cutting?

History

– Where does the word “involute” come from?

The term “involute” comes from the Latin word “involūtus,” which means “rolled up” or “entangled.” The name is derived from the geometric construction of the curve. In mathematics, the involute of a curve is a path traced by a point on a string or a taut wire as it unwinds from the curve. Imagine a string tightly wound around a curve, and as you pull the string, it unwinds and traces out the involute curve. This construction is particularly interesting because the involute has some unique properties that make it useful in various applications.

One important property of the involute is that it guarantees a constant tangent to the original curve at every point along the involute. This property is what makes the involute useful in certain engineering applications, including the design of gears and turbine blades. The constant tangent property ensures smooth and efficient motion and operation in these applications.

The concept of involutes has been studied since ancient times. Early mathematicians like Archimedes and Pappus of Alexandria explored certain curves that are now recognized as involutes. However, the name “involute” and its formalization in modern mathematics can be attributed to prominent mathematicians such as Jakob Bernoulli, who worked on the topic in the 17th and 18th centuries.

Today, the term “involute” is widely used in mathematics, engineering, and various scientific disciplines to refer to curves, shapes, and profiles that exhibit the specific properties associated with the involute construction.

– Where does its use in meat slicing come from?

The concept of the involute curve, which is the basis for the design of the involute blade, has been known for centuries and was first described by the Swiss mathematician Leonhard Euler in the 18th century. Engineers and scientists later recognized the advantages of using the involute curve in the design of turbine blades for steam and gas turbines. Turbine blades with involute profiles have proven to be efficient and effective in converting fluid (steam or gas) energy into mechanical work, which is crucial in power generation and other industrial applications.

The use of involute blades in meat slicers and other food processing equipment is a more recent development, and it likely stems from recognizing the benefits of the involute profile in terms of cutting efficiency, smooth operation, and reduced energy consumption. The involute profile allows for a constant cutting force along the entire length of the blade, making it suitable for precision cutting tasks.

Overall, the use of involute curves in mechanical engineering and its application to various fields, including turbine blades and meat slicers, showcases how mathematical principles and engineering concepts can find diverse and innovative applications in different industries over time.

Blade Options

The options are a straight-edge, a circular or an orbital.

The Involute in Meat Slicing

Bremer (2021) did experimental research to validate theoretical models on the complex interactions of food and blade, which determine the cutting forces. The paper is available for download below.

– Process Description

“High-throughput slicing is performed using involute blades. The cutting edges of involute blades have the form of a spiral. Thanks to this geometry, the blade cuts while rotating around a steady center allowing for a continuous process, while cutting with a slicing and pushing motion. After cutting, the blade is no longer in contact with the food. During its remaining rotation, the food is moved one slice thickness beyond the cutting plane. With large blades, as compared to the food cross-section, multiple pieces of food can be cut in parallel. After a slice has been cut off by the blade, it lands on a conveyor belt or on previously cut slices.” (Bremer, 2021)

– Considerations

Considerations when evaluating blades are:

• damage done to the meat muscle while slicing
• the speed of the slicer. Bremer (2021) shows very clearly that 1200 rpm gives greater distortion to cooked ham slices than, for example, 600 rpm.
• The kind of meat sliced
• Slicing temperature
• Percentage extension

Bremer deals with the matter in far more technical detail where my consideration points are based on the observed outcome.

– Things to consider related to the slicing of cooked hams

1. Straight Edge:

• The straight-edge cutting system is the simplest and most common method used in many slicers.
• It is suitable for slicing uniform thicknesses and works well with products that have a consistent texture and density, like certain types of deli meats.
• However, it may not be as efficient or ideal for slicing certain irregular or softer textures, such as cooked ham, as it can cause tearing and uneven slices.

2. Orbital (Circular) Blade:

• The orbital cutting system utilizes circular blades that move in a circular or orbital motion, slicing through the product as it rotates.
• This system can handle more delicate and softer products like cooked ham better than a straight edge.
• The orbital motion can result in cleaner, smoother slices with reduced tearing.
• It is also suitable for high-volume slicing operations and can increase throughput compared to straight-edge systems.

3. Involute Blade:

• It is often used in high-volume slicing environments.
• The involute blade can offer excellent slicing efficiency and precision, producing consistent thickness slices with minimal tearing.
• For high-quality and precise slicing of cooked ham, the involute system can be a preferred choice.

– What About Bacon Slicing?

When it comes to slicing frozen bacon while minimizing meat loss and achieving high-speed/volume slicing, the involute system is generally considered the most suitable option among the three choices (straight edge, orbital, and involute).

The reasons are the following:

1. Minimizing Meat Loss: The involute cutting system, with its constant cutting edge along the blade’s length, offers precise and consistent slicing. This design allows for minimal meat loss during slicing, especially when dealing with frozen bacon. The constant cutting action ensures smooth and efficient slicing without tearing or excessive wastage.
2. Efficient Slicing at Frozen Temperatures: Slicing frozen bacon requires a slicing system with sufficient power and precision to handle the hard and brittle nature of the product. The involute system, with its robust blade design and continuous cutting motion, can effectively handle frozen bacon at high speed and volume slicing without compromising slice quality.
3. Reduced Friction and Heat Generation: The involute blade’s design helps reduce friction during the slicing process, which is beneficial when dealing with frozen products. Lower friction means less heat generation, helping to maintain the integrity and quality of the frozen bacon slices.
4. Consistent Thickness Control: The involute system allows for precise control over the thickness of the bacon slices. Consistent thickness is essential for maintaining the product’s appearance, texture, and cooking characteristics, especially when slicing frozen bacon for commercial purposes.

While the straight edge and orbital systems have their advantages, such as simplicity and suitability for certain applications, they may not be as effective or efficient in slicing frozen bacon while minimizing meat loss. The orbital system could potentially handle frozen bacon better than the straight edge due to its circular blade motion, but it might not match the precision and efficiency of the involute system.

Overall, the involute cutting system is well-suited for slicing frozen bacon at high speed and volume while ensuring minimal meat loss and consistent slice quality.

Conclusion

This overview helped me to make sense of the options and considerations when evaluating the blade options for slicing meat.

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References

Bremer, F., Matthiesen, S. (2021) High-speed cutting with involute blades: Experimental research on cutting forces, Journal of Food Engineering, Volume 293, 2021, 110380,
ISSN 0260-8774, https://doi.org/10.1016/j.jfoodeng.2020.110380.