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IWF ATLANTA REGISTRATION 2_19_24
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Who is the stepchild in your woodworking shop?

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A smart machine design with chip collection openings.


Everyone needs it, but the dust collector is seen as a necessary ‘evil’ and has none of the allure of your actual production machines. It does not add value to your product directly, but wherever dust or chips are produced, they have to be safely and efficiently collected and disposed off.

Here are some of the reasons why:
• First of all for safety reasons. Wood dust is a major fire and explosion hazard.
• Also, airborne dust is a health issue. Inhaling fine wood dust for prolonged periods will cause problems in the respiratory systems of your exposed workers. Dusts of some wood species are even classified as cancer-causing. Several organizations have set standards or given recommendations for wood dust exposure, which include Occupational Safety and Health Administration (OSHA), The National Institute for Occupational Safety and Health (NIOSH), and the American Conference of Governmental Industrial Hygienists (ACGIH). For example the ACIGIH recommends a max. air contamination of 0.5 mg/m3 for Western Red Cedar.
• If chips are not removed they stay in the cutting area and will be cut again and again. This leads to a reduction of tool life, higher tooling and energy costs. In addition, re-cutting creates much finer particles, which pose a greater hazard.
• Last but not least, a clean workplace increases efficiency and boosts worker morale.

A dust collector is a vital part of your plant or shop.
I will not go into details on how to design a dust collection system. There are specialists who will help you to specify the correct layout for your present and future requirements. But I do want to highlight the importance of a good dust collection system. It has a direct impact on your bottom line through, for example, rework, tooling and energy costs. It also improves the quality of your products, which in turn affects your reputation.
In many shops the dust collector is one of the largest electricity consumers. It is the first machine in the shop to be started up in the morning and the last to be turned off. This creates a great opportunity for energy savings.
With a dust collection system it is the same as with any other capital investment in your shop – you get what you pay for. Investigate the options and the benefits of the various technologies before making a decision. A dust collection system cannot be reduced to the size of the main motor, because it says (almost) nothing about the effectiveness and/or efficiency of the system, but may give you the wrong impression that you got more for your money than you actually did. The most important factor for the system is the amount of suction at the machine, which means the flow rate of air transporting dust and chips from the tool in the machine to the dust collection bins. This flow rate is measured in cubic feet per minute (CFM) or in cubic meters per hour (m3/h). The conversion factor from CFM to m3/h is approx. 1.7, e.g. a dust collector of 1,000 CFM equals 1,700 m3/h.

The electricity consumption of two dust collectors with identical CFM performance can vary by a factor of four, meaning that if both systems supply the same air flow at the machine, one system may require four (4) times as much energy than the other. The reasons for these vastly different energy requirements can be:
• The type of motor (energy efficiency)
• The way the motor is started (hard or soft)
• The RPM of the motor (constant or variable)
• The connection of the motor to the fan (direct or via belt)
• The efficiency of the fan. The design of the fan has a big influence on the energy efficiency of the dust collector. A well-designed fan blade will create the required vacuum or negative pressure, which is measured in ‘Inches of water column,’ much easier and more energy efficient than a straight fan blade. (See photos of two different fan designs).

Let us look at the example of an average shop with about 10 standard machines to demonstrate the possible range of solutions. Let’s assume the dust collection system for this average shop requires a capacity of approx. 4,000 – 6,000 CFM. A simple indoor system with hard start will cost approx. $7,500, whereas an outside system with air return and hard start will set you back around $30,000. The upgrade to a soft start of the motor will add about $5,000 to either system. A fully loaded exterior dust collection system with variable frequency drive and 10 servo driven gates (one at each machine) will add up to around $55,000.
As you can see the price spread for possible solutions is huge, but you have to look closely at the potential savings each of them offers. The smart gates at each machine, which open and close when the machines are switched on and off, and the variable frequency drive (VFD), which allows the air flow to be regulated closely to the actual demand, bring a significant drop in electricity consumption. A surprising side effect is the substantial noise reduction.
On top of the electricity consumption, you also have to consider peak power requirements. An uncontrolled or ‘hard’ motor start will create a power peak of up to 10 times the nominal current of the motor on start-up, which the power provider will charge you for. Just to turn on your dust collector can be very costly.
With today’s electricity prices the return of investment for a ‘smart’ dust collector is in most cases less than 12 month, and government grants can further shorten the payback period.
One last consideration: not only the design of the dust collector has influence on how good and efficient the chips are collected and removed. The tooling and the machine also play an important role in maximizing the dust collection efficiency and minimizing the associated costs. Tooling and machines need to be designed to transport the chips away from the blade and guide them towards and into the dust hood to reduce required airflow.
Today’s manufacturers use extensive laboratory testing with high-speed cameras and other equipment to find ways to create the best possible dust collection flow with the least amount of energy required. A smart machine design with chip collection openings where they are needed and an assisted airflow to guide chips to them (see photo above) will significantly reduce the required airflow. The photo shows the dust collection system of a beam saw. The chips created in the cutting process are thrown against the machine bed at the right side (the saw blade is cutting from left to right). The holes of the dust extraction system in the machine frame are arranged in a way that the chips can continue their path directly into the collection funnel. The flow direction of the chips doesn’t have to be changed and there is no dead corner where the chips will settle and accumulate. Furthermore the dust removal system is supported by special air jets, which are transporting the chips to the right towards the dust collection funnel.

Christian Vollmers is the president of HOMAG Canada Inc. He can be reached at Christian.Vollmers@homag-canada.ca, or visit the website at www.homag-canada.ca

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