Importance of Blade Sharpness in Precision Manufacturing

Keeping cutting knives sharp is of utmost importance in any factory setting, particularly when there is a need for accurately cutting delicate substrates and materials by hand.

Scalpel blades are used in many manufacturing processes, where precise hand cutting is preferred over machine cutting.  Delicate textiles, carbon fibre cloth, leathers, specialist materials where automation set-up errors can quickly turn expensive, and custom cutting work often call for hand knives.

These industrial processes that require sharp scalpel knives use a cutting mat to prolong the precision cutting ability of the blade, increase operator control and protect the work surface.

Standard workbench surfaces made from MDF and the like, take the keenness off a precision blade’s edge from the first cut!


The 4 Most Important Reasons To Maintain Your Production Blades Sharpness:

Here are some of the reasons why it is important to keep a cutting knife sharp in any factory setting:

Safety: Using a blunt knife requires more force to make a cut, increasing the risk of accidents and injuries. A sharp knife, on the other hand, glides through the material being cut with minimal effort, which increases operator control and reduces the likelihood of accidents.

Efficiency: A dull knife takes longer to make a cut and may require multiple passes to complete the cut. This leads to a slower production rate and ultimately, a decrease in overall efficiency. In contrast, a sharp knife can make clean, precise cuts in a single pass, allowing for a faster production rate.

Accuracy: Blunt knives are more likely to produce uneven or poor-quality cuts, leading to waste and the need for rework. A sharp knife, on the other hand, can produce clean, precise cuts, resulting in better-quality products and fewer defects.  Any damage to the blade edge will give it a tendency to veer off the line being cut.

Cost: Using a dull knife can lead to increased waste and the need for rework, resulting in higher costs. In contrast, maintaining a sharp knife blade can help reduce waste, (of time and material) for increased efficiency and better use of resources.

Being Razor-Sharp On Safety

Putting safety first, let’s consider the safety aspects of knife work.  A USA study found 30% of all general workplace injuries are cuts or lacerations, of which 70% involve the fingers and hand.  In a factory setting where handwork with knives is unavoidable, the industry injury figure is potentially a lot higher than this.  According to the British Safety Industry Federation, 25% – 50% of time-off-work accidents in the UK plastic processing industry were due to cuts, whilst knives were responsible for 58% of all manual tool accidents.

A sharp blade slides through the material with very little effort and in a predictable manner that makes it much easier to ensure the safety and efficiency of the cutting process.  A dulled blade requires more effort and can lead to a sudden loss of control, increasing the chances of a dangerous slip – as well as the depth of injury too.

The approach advocated by the Health & Safety Executive (HSE) is to first engineer out the risk entirely if reasonable, then to deal with any remaining risk through controls and PPE.  Whilst each process and site needs its own risk assessment undertaking, the HSE publishes some very useful and practical guidance, including this 8-step knives at work action plan.

In certain industrial processes, it is not possible to remove the need for hand knife work due to the nature of the product and project being worked on.  Fixed-blade knives might be the only type found suitable for the task in hand, or a retractable knife from the HSE termed “Group 4” or “Group 5” type safety knives.

The PUWER 1998 (Provision and Use of Work Equipment Regulations 1998) covers knives in the workplace as also the Health & Safety at Work Act.   If knife work is needed in your process, here’s a quick summary of considerations:

  • Which knife/knives are suitable for the cutting task/s? This is likely to involve supplier information, trials, and consultation with users.
  • Safe for use, maintained and inspected to ensure it doesn’t deteriorate. As blades are a wearing part, it is important to have spares available and a plan to change them safely.  Avoid knife edge damage by preventing blades from rubbing or knocking against hard surfaces.

A round-tipped blade may be suitable for some softer materials.  The blade shouldn’t be excessively longer than needed, it should cleanly cut the required material without operator strain and be strong enough to function correctly.

  • Only used by those trained and instructed.
  • Knife storage and transport. Knives should be kept accessible; to those who need them and at their appointed workbench.  Avoid having to carry knives from one workstation to another location, mobile operators should use a safety sheath and/or retractable blade.
  • Suitable controls and PPE are provided to reduce residual risks to an acceptably low level.

As hand knife injuries are usually the result of the knife slipping during cutting and trimming work, it is important to remove any inconsistencies in the process, and also in the working environment.

This consistency aspect takes us neatly to the efficiency effect of using sharp blades in manufacturing….

Hand Tool Cutting Efficiency

Applying LEAN principles results not only in greater safety but exponentially greater efficiency and predictable output.  LEAN  includes a floor and workbench free of debris and clutter.  As is also having the right tool for the job, in the best place and with an informed, repeatable process.

Disposable scalpel blades are used in most handwork involving paper, textiles, leather and leatherette.  These lightweight and compact knives allow for intricate cutting and are often either the snap-off type or clip-off surgical blades.  Carbon steel is often used for quality blades as its hardness makes for sharper cutting edges that last longer than ‘softer’ metals.

Sharp Blades For Better Accuracy

Surgeons will tell you that the first cut with a new blade is always the sharpest, however, in most manufacturing applications a blade should usually be expected to make hundreds of cuts before needing to be replaced.  However, it’s worth bearing in mind that as the blade dulls, it will become more at risk of tearing the material or wander off line easier.  For this reason, if your process involves cutting a number of different materials with such as paper, card, leather or hardboard, it is best to keep the newest blades strictly for the paper.  Once they have been used on more course material such as plastic or card, they could be ruined for their original fine paper use.

Likewise, if cutting paper on a hardboard bench then using a soft cutting mat will not only preserve your work surface but ensure you get maximum use from your precision knives.

Blunted, dulled or damaged blades result in uneven or poor-quality cuts, leading to waste and inefficiency in the production process.  Even a single knock against a metal surface can spoil a blade’s keenness.

The Importance of Cutting Straight and True

Although somewhat independent of knife sharpness, it is important to remember to keep the blade running ‘true’. Usually this would involve running it against a straight-edge, but for more complex cuts this depends on careful handling of the knife or use of a template. If the blade is allowed to wander or run at an angle, the tendency is for the knife to gouge into the mat, eventually breaking away pieces of it, and greatly reducing the lifespan of the cutting surface. The following two photos show the difference between repeated cuts where one is kept straight and true, the other is allowed to be angled off centre.

Two images, one showing cutting with a blade running straight and true, the other when the blade is allowed to wander and go at an angle.

Take Care Of Your Knives And Your People So They Take Care of Your Quality

In summary, keeping cutting knives and blades sharp is crucial in any workplace setting for the safety, efficiency, quality, and cost of the manufacturing/trimming process. It is important to care for the edge of your knife blades as any damage or dulling of the edge affects the safety, efficiency, and quality of the cutting operation.  Blades are either made as re-sharpenable or disposable, so ensure your routine maintenance and staff training takes this into account.  Minimise the risk of accidents, and provide correct training, equipment, and PPE.

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