Making plane sense
Planer maintenance and adjustments are often overlooked and poorly documented, a free-for-all that in the end is far from free.
By: Benoît Laganière & Scott Jamieson
The planer is the piece of equipment with the most adjustable parts in any mill. Ironically, it is also one that often sees the least attention. All the elements that make up a planer are critical, as they can influence both the movement of the piece through the planer and the production pace, both crucial now that value is recognized as the key to wider margins, and as most planers struggle to keep up with modernized, high-speed sawmills. For maximum performance, rough lumber being fed through the planer must move as little as possible, and be subjected to the absolute minimum of constraints while planing occurs.
All of this assumes a properly aligned, levelled and maintained planer. After conducting over 50 planer mill seminars and inspections across Canada, I can assure you that few sawmills should take this for granted. While some planer mills are doing a good job on this front, others I visited were in such bad shape that it was a wonder they pushed any wood through the planer at all. Don’t even get me started on planer mill downtime, a statistic that few mills even bother to track.
Still, all is not lost. Following are a few things to keep in mind as you strive to maximize the return from your planer. More detailed information can be obtained from Forintek Canada Corp.’s Planer Adjustment Tools Manual, High-speed Planer Adjustment Manual and Process and Quality Control Procedure – Planer, all available online at www.forintek.ca.
1. Ideally your planer should be level. If not, at least ensure that all of the elements are on the same axis. All plates, rolls and the rest should be at the same level (or un-levelled along the same plane). This will avoid bending lumber during planing. Above all, the plates must align with each other, as the planer is like an industrial milling machine, only in this case it’s the piece that moves rather than the cutting tools.
2. More often then not, the depth of cut is unknown, and is not measured on a regular interval. To avoid planer skip, the operator often takes a bigger bite, but without realizing the clearance he is creating behind the cutting circle. Such clearance should sit between 0.005" and 0.015" for all cutting tools, with 0.020" being manageable but certainly undesirable. The depth of cut of the bottom cutter head is adjusted by moving the planer bedplate, so that if the rear clearance is too large, the lumber pieces will not be supported, resulting in a wave effect.
The depth of cut will depend on the amount of wood available to the planer. Operators must measure the rough lumber thickness and adjust the depth of cut accordingly. Some mills could plane to a depth of just 1/32", so that it’s worth considering that 1/16" (0.060") needn’t always be the target.
3. The position of the four infeed rolls is very important. If the rough lumber does not contact the bedplate directly below the chip breaker, the chip breaker will end up pushing the piece down. This will not only constrain the piece being planed, but will also force the next piece to push harder to force the first one through, slowing production and causing premature wear on the chip breaker.
4. On that subject, premature part wear indicates improper adjustment. If wear starts to show three to six months after installation, it’s safe to say your planer is out of whack. You can also bet you are losing production and quality.
5. Helter Skelter may have been a good song, but it’s no way to run a planer mill. Most mills lack established, written methods for planer adjustment. Operators do as they please, logbooks are seldom kept, and when the shift is over, all references are lost and the new operator starts from scratch. It’s a free-for-all in which no one knows what happened last shift, let alone last week. Oh, and it’s not really free.
6. The number of knife marks per inch typically determines your lumber surface quality. If this falls below 3.5, your tool edges must be in perfect condition and your heel no wider than 0.030" (1/32"). Otherwise you risk torn grain. With five or more knife marks per inch you can fatten your heel to 1/16" if you wish. In any case, ensure you grind your knives as often as possible. The ideal is once an hour, and often all that is needed is a few light passes to refresh the edge. Remember – Fireworks are prohibited. New fast head or knife installation systems are recommended, as knife changes will be done more often, and dull knives will not risk damaging your fibre anymore.
When thinking of cutting tool maintenance, remember that running a planer is not unlike running a circular saw. A saw will not cut wood if the teeth are dull – you can force it to, but the teeth and plate will overheat, and over time the motor will be damaged. It differs slightly for the planer, as the motors are much stronger compared to the work being done. Nonetheless, you are forcing the components. For the same reason you’d never plane by hand with a dull tool (excessive force and poor results), don’t do it with your planer mill.
7. A shiny lumber surface is not really a sign that all is in order, as it still may have come at the cost of the piece being subjected to excessive force and the planer feed speed being reduced.
8. Operators usually rely on the existing planer adjustments or those made by installation contractors. This can be dangerous, as often in these cases the equipment is not adjusted correctly, as it was done over a weekend, ahead of vacation breaks, and by personnel lacking the proper know-how to do it properly.
9. That new-car smell is no guarantee that everything is perfect under the hood. I have seen planers less than a year old that are very badly adjusted, as well as planers older than dirt that are very well adjusted. In the end, the basic principals behind planing have not changed.
10. A lack of training and continuous training, a lack of information exchange between personnel, a shortage of visits and exchanges between planer mills, and high rotation rates among mill personnel all conspire against improvement in planer mill performance and tuning. Of course it helps if you schedule time for planer tuneups to occur.
11. The out-dated design and lay-out of most planers, especially older models, also conspires against planer maintenance and tuning. For those used to modern production machinery, visiting a planer mill can be like stepping back 50 years in time – components are oversized, heavy and difficult to access. It often requires two mechanics to perform a proper tune-up, increasing costs and decreasing the likelihood that it will be done at all. Planers like the new models from Gilbert in which the cantilevered feed rolls easily move out of the way greatly facilitate basic maintenance, tuning, and operation, since if a piece breaks it is easily accessed.
12. A pile of broken lumber ends scattered on the ground or pointing out of the walls and ceilings is a good indication that it’s time to open up the planer and have a serious look. So too is a staff that is afraid to walk through the planer room.
13. Planer components on their own should not run hot enough to start fires, unless there is a seriously undersized water cooling system.
14. If your planer staff continues to ignore all the above in the name of today’s production, you may have a UFO on your hands – an Uncontrolled Fixed Object.
Benoît Laganière is a researcher with Forintek Canada Corp. who in recent years has focused on debarkers and planers. This article is based on his experience in conducting over 50 planer mill seminars, and was written exclusively for Canadian Wood Products Magazine with the help of Scott Jamieson, editor. In a future issue, he will look at common lumber defects and their roots at the planer.
