We have made SmartBench as safe as possible, but as with any CNC machine, there are still some fundamental safety precautions that the operators need to take. 

Read the following articles in full. Ensure that you understand the risks involved in CNC machining and using SmartBench, and that you have appropriate safety measures in place prior to operating SmartBench.

In the event of an emergency, turn off the machine by pushing the power button on the Lower X Beam:

Be aware that if SmartBench is switched off during operation: 

• The machine’s position will be lost. It will need to be rehomed and the job restarted.

• If the tool is stuck in the materialy you will need to manually remove it from the workpiece, as per the instructions in the next part of this article. 

If you carry out an emergency power down mid-job, you may need to manually remove the tool from the workpiece before turning SmartBench back on. Click here to learn more about this. 

SmartBench’s Upper X Beam has two Interrupt bars, which are designed to auto-detect obstacles in SmartBench’s workspace. 

When the Interrupt bars make contact with an obstacle, they will be depressed, and SmartBench will stop and pause all active jobs or operations. 

A: Interrupt bars

After SmartBench has been paused by an Interrupt bar event, the operator will have the option to cancel or resume the job. 

Click here to learn more about what you need to check before resuming a job, and when you need to cancel a job after an Interrupt Bar event. 

All CNC machining, by its nature, produces a lot of heat. As the cutter moves through a material at high speeds, it produces very high levels of friction. This frictional energy is ultimately converted into:

• The energy used to break through the material.

• Heat energy.

If the amount of heat energy produced by the cutting process gets too high around a combustible material (e.g. wood stock), there is a risk of fire. 

Reducing risk of fire

The first tenet of fire safety is to reduce the risk of fire. 

There are three key elements needed to cause a fire: fuel, oxygen, and heat. These elements make up the fire triangle. 

During routing, all three elements of the fire triangle are present:

However, the operator can take precautions to reduce the likelihood of these factors (or the combination of them) reaching critically high levels.

Oxygen

Extraction pulls oxygen through the work area. If we want higher airflow for our extraction, it will naturally force more oxygen to travel through the work area. 

However, good airflow is completely necessary for removing waste from the cutting site, which in itself reduces fire risk. 

Therefore, we need to focus on minimising the other two elements of the fire triangle: fuel, and heat. 

A: Extraction hose

B: Working zone

C: Air flow direction

Fuel

For a fire to start there must be a material to burn, i.e. the “fuel”. Fuel can come in the form of any combustible material. 

The moisture content, size, shape and quantity of the material will all determine how easily and at what temperature it will ignite or burn. 

Cutting any combustible material is a fire risk

Cutting any combustible material (e.g. timber) means that there is a risk it can catch fire. 

Different woods will have different natural properties which can affect their combustibility.

• Resins, found in woods such as birch or pine plywood, can act as an accelerant (i.e., speeds the development or escalation of fire).

• Natural variations in the material can generate sudden and unexpected increases in heat as the cutter passes through it.

Before cutting any combustible material, make sure you use the right cutter type and cut with the right feed and speed settings for that material.

Click here to learn about the right cutter type for specific material.

Click here to learn more about SmartBench feeds and speeds for specific materials.

Moisture content

When wood is in storage it acts as a sponge, absorbing moisture from the air. If the air is dry, the wood will become dry too. The drier the wood, the higher the risk of it catching fire. 

In the context of firewood, logs with higher than 30% moisture content would struggle to burn. A typical firewood moisture content would be 15 – 20%. Firewood with less moisture content is not even recommended, since it will burn so hot that it can actually damage a stove! 

What do I need to do?

Monitoring and controlling air humidity is a good way to control your wood stock conditions. Note that moisture content in the air drops with a drop in ambient temperature.

Here is an example of historic data on air humidity in our factory in the UK:

From the graph, we can see that the humidity level never drops below 30%, so during this period we knew that our wood was low risk. 

Make chips, not dust

When routing, always aim to generate chips, not dust.

Dust has a high air surface to fuel ratio: this means that for each piece of dust, the combustible molecules that make it up are more likely to be in contact with an oxygen molecule in the air, which means better conditions for starting a fire. 

Due to their shape and volume, chips of material have a much lower air surface to fuel ratio: so each fuel molecule is far less likely to be in contact with an oxygen molecule. 

Creating chips instead of dust means that there is a lower proportion of the available fuel (i.e. the cut material) mixing with oxygen in the air, so the fire risk is reduced. 

Chips also hold on to excess heat more effectively than dust, so when they are extracted, they take that excess heat with them – away from the cutting site. 

D: Chips

E: Dust

To create chips instead of dust, make sure you: 

• Choose a cutter designed specifically for the stock material that you are cutting. Click here to learn more about choosing the right cutter. 

• Make sure the feed rate is fast enough for your job. Click here to learn more about choosing the right feeds and speeds for your application. 

Extract waste (a.k.a., excess fuel)

If waste builds up around the cutting site:

• It can prevent excess heat from the cutter from dissipating, as the waste (already warm from being cut) is acting as an insulator around the cutter.

• It increases the amount of readily available fuel at the cutting site, should anything ignite. 

Therefore it is important to maintain good extraction throughout the job. 

It is easy for extraction to fail, due to full vacuum bags or blockages, but a few simple checks can significantly improve reliability:

• Always empty the extraction bag before a job, regardless of level, to ensure that the highest possible draw is achieved. This reduces risk of failure due to reaching vacuum bag capacity. 

• Pause the job if you need to empty the vacuum bag. Once the bag is emptied, you can resume the job.

• Always do a manual check for any blockages prior to starting a job: pulse the extractor on/off with a hand over the dust shoe aperture, to check the airflow. If there are any issues, do a thorough visual inspection of all hoses to check for blockages. 

• Do regular visual checks of the cutting site; if there is a build up of waste, pause the job and do a thorough check of the extraction. 

Heat sources

A heat source causes the initial ignition of a fire. Reducing the friction between a cutter and material is the main way to reduce the amount of heat the friction produces. 

Blunt cutters get hot

As a cutter loses its sharpness, it generates more friction, which makes the cutting tool hotter. 

To overcome the extra friction, the spindle will demand more electrical energy to maintain speed, and this extra energy will continue to get dissipated into the material through friction, creating more heat.

F: Cutter in original good condition.

G: Cutter has been exposed to high temperatures and overheated.

Pick the right cutter type for the job

The best cutter to use is a cutter that is designed for a specific material. Using the wrong type of cutter will make an inefficient cut, which will increase the amount of heat and dust.

Click here to learn more about cutter types.

Down cutters and compression cutters increase friction and heat

Downcut flutes produce a better finish on the top surface by forcing waste downwards, but they achieve this by compacting dust into the channel of the cut. This will make it harder to evacuate cutting waste, and may contribute to increased friction and heat.

Earth your extraction equipment

High airflow extraction is essential for any CNC job, but through a plastic or rubber tube it also naturally generates static electricity. 

Extraction equipment, including the length of the hose, needs to be earthed. If the extraction system is not earthed, static electricity will build up, and if it reaches a critical level it will discharge to the nearest earth in the form of a spark. 

If the nearest earth is a big metal SmartBench (which is very likely), this spark is enough to ignite chips and dust particles around the cutting site. 

Click here to learn more about earthing, and how to earth your extraction system. 

Containing an ignition

Do not leave SmartBench unattended

Never leave the job unattended.

It’s tempting to let SmartBench do it’s own thing – after all, isn’t that the point? But the reality is that the machine won’t know if it’s run into trouble, and you need to be there to deal with any issues if necessary.

Extinguishing a fire

Not every fire is the same, and using the wrong type of fire extinguisher could make things worse. 

Fire extinguishers are developed to eliminate one of the three elements of the fire triangle: 

• If we remove fuel, the fire will smoulder out.

• If you can cool a fire down it will lose heat and go out.

• If the oxygen is removed it will suffocate. 

It is therefore important to match the right type of fire extinguisher to the correct class of fire. 

Fire classification

Whilst there are 6 different types of fire class, for SmartBench we have shortlisted 3 relevant classes:

• Class A: fires caused by ordinary solid combustible materials such as wood, paper, cardboard and textiles.

• Class D: fires caused by combustible metals such as potassium, aluminium or magnesium.

• Electrical fires: Caused by electrical equipment. Note that this fire will change class once the electrical item is shut off or removed (and will then be classed based on the combustible material).

Keep a suitable fire extinguisher on site

The following table shows you which type of extinguisher is suitable for each class of fire. 

To identify fire extinguisher type, look for the label on the front: 

Machining materials (such as wood or metal) causes small particles of dust to become suspended in the air. These suspended dust particles possess the following risks to health:

• Inhaling dust can cause serious breathing problems, including but not limited to:

  • Asthma.

  • Cancer of the nose.

  • Cancer of the lungs.

• Machined dust can cause eye irritation.

• Exposure to machined dust can cause various skin conditions. 

Ways to control exposure to dust

Dust extraction

Ensure your extraction system is Class M or higher, and has a minimum airflow rate of 50 litres/second to remove and contain dust from the work area.

Respiratory protective equipment (RPE)

Provide operators with respirators to protect against airborne material dust. An example of the respiratory specification is shown below.

Site regulations and further information

If you are using SmartBench on a professional job site, you may be subject to local working regulations concerning dust from machining. 

Click here to see the NSW government’s Health and Safety information regarding wood dust. 

Noise is part of everyday life, but harmful levels of noise can lead to serious health and safety issues such as hearing loss or tinnitus. 

Over time, an uncontrolled consistent exposure to the loud noises from machinery and tools may lead to a permanent hearing loss.

It is important to know whether the noise levels from your working environment pose a hazard to health, and to wear appropriate ear protection to preserve your hearing.  

How to measure the level of noise?

In order to check whether the noise level for your manufacturing environment has a potential noise hazard, use a sound level meter.

Image credit: Tekcoplus

SmartBench sound pressure

SmartBench has the following sound sources:

• Spindle motor (A)

• Extractor (B)

• Resonance in the job while machining

• Contact between material and a tool

• Chassis movement

SmartBench operating noise level 

When only SmartBench was operating, we measured the maximum noise level to be 80dD (decibel).

SmartBench sound level with extraction 

The maximum noise level with both SmartBench and an extractor operating was recorded as 87dD (decibel).

C: SmartBench

D: Extraction

Evaluating SmartBench sound intensity

By comparing our measurements to the chart below, we can see that SmartBench on its own doesn’t cause much noise hazard. However, when the extraction system is switched on the noise level tends to be harmful.

Different extraction systems will have different noise levels, so we strongly recommend that you check the noise levels of your system to ensure site safety, and so that you can implement appropriate precautions. 

Image credit: Soundproofing Guide

Hearing protection  

If the noise level for your environment is harmful, it’s important to take precautions to protect your hearing. You can do this by using:

Ear defenders

Disposable ear plugs

Safety glasses are an important piece of equipment to protect your eyes. 

There risks to eyes associated with CNC machining are as follows: 

• Material debris being ejected from the cutting site.

• Exposure to dust from the cutting site.

• Pieces of cutter ejected from SmartBench, in the event of tool breakage. 

SmartBench’s extraction will mitigate these risks, but you should still wear safety glasses whilst operating SmartBench, should something unexpected happen. 

Image credit: screwfix

Using the wrong type of cutter will not only ruin your job, but it can also cause serious harm. 

Tool breakage

The cutter in SmartBench, depending on the set spindle speed, is probably rotating between 12,000 – 25,000 RPM. 

If the cutter breaks, the broken pieces of metal will be ejected from the cutting area, at very high speed. 

These cutter shards could impact an operator, causing potentially serious injury. 

At best, this will cause damage to the workpiece, and potentially damage to the spindle. 

Example

Here is an example of a drill bit used on SmartBench. By design, a drill bit is not intended to be used in speed machining (it is used at comparably low RPMs); at high RPMs the drill bit may start to deflect as shown in the image. Once the deflection has started, it will not take long for the drill bit to break.

Overheating

If the wrong cutter is used in the wrong environmental conditions, it can lead to overheating to such a high extent that there is a fire risk. Read above to learn more about this.

A: Cutter in original good condition.

B: Cutter has been exposed to high temperatures and overheated.

Risk prevention: understand your cutters

It is important to choose the right tool and settings for the job. Click here to learn more about cutters.

Injuries due to lifting can have serious consequences. You could be putting your back, shoulders, knees and other joints at risk of injury. 

To help prevent injuries in the workplace follow the proper lifting techniques.

Plan the lift before you start

Before lifting or carrying, think about:

• How heavy is the load?

• Does packaging need removing?

• Is your workholding clear of obstacles to accept the stock material?

• Do you need assistance in lifting the stock material?

Lift from a stable position

Get as close to the stock material as possible. 

Position your feet in a wide stance in order to develop more power while you lift and also to improve your balance and stability. 

It is also important to not wear over-tight clothing or unsuitable footwear, which can make lifting more difficult.

Bend your knees rather than your back

At the start of the lift it is better to bend your knees and hips, and keep your back straight, so that you do not strain your back. 

Tighten your abdominal muscles to stabilize through your core in preparation for the lift. 

Keep the load close to your body

While lifting, keep the load close to your waist; this puts less strain on your back. 

Avoid leaning, twisting, or bending your back as this places pressure on the spine. 

Instead, move your feet to turn by keeping your whole body shoulders, hips, knees and toe facing the same direction. 

Maintain your head level and look ahead, not down at the load, once you are holding it securely. 

Put down, then adjust 

Put down the stock material on the spoilboard or the bed of the Y Bench, without positioning it yet. 

Once the weight of the stock material is fully supported by SmartBench, then do the finer adjustments to position it. 

Use mechanical aids whenever possible

If possible, make use of lifting equipment, such as forklifts or pallet trucks. This will help with lifting and transporting heavy stock material.

Loose cables can increase the chances of tripping. Trip occurs when a person’s foot is obstructed, which results in a loss of balance, leading to a potential injury.

Image credit: Healthy Project 101

SmartBench has trailing cables, which may present a trip hazard if not laid safely. 

The picture below shows the scenario:

Preventing cable hazard

To prevent cable tripping hazard, do the following:

• Ensure cables and extraction are under the SmartBench to avoid tripping. Make sure the cables have enough reach to freely move along the bench without catching on any obstacles.

• Use a floor cable protector to keep cables safely covered to avoid tripping and damaging them.

• Always use the cable strain relief to securely clip the power and extraction cables to avoid them being pulled loose while the machine is in operation. 

• Poor or low lighting will prevent people from seeing cable hazards. Ensure the room where SmartBench operates has proper lighting.

Safety of an operator should be the topmost priority of any procedures carried out using SmartBench. 

Anyone operating SmartBench should adhere to the safety measures outlined below:

Pacemakers 

Clothing 

Long hair 

PPE