Maximizing Feed Table Efficiency
How to get the highest performance out of your feed table
In many mills, it is the feed table that needs a lot of attention. It is often the weak link in the system. In order to increase production and up-time, the feed table must operate at maximum efficiency and be very consistent. By increasing the efficiency and precision control of the feed table, speeds can be lowered to within 3% of planer speed, providing better control of the lumber – eliminating many issues caused by forcing pieces through the planer with the feed table. The set-up of the planer is also very critical to get a good feed of lumber. The planer should be able to feed one piece at a time. If this isn’t happening it could be a number of issues. Please call for our planer set up procedures.
The shear, table and rolls have to work together to obtain a smooth flow of product into the planer. Our experience shows that transfer chains must deliver the lumber to the proper place at the beginning of the spiral bed rolls, allowing the lumber to use the entire bed roll. This insures that the lumber is driven to the shear. Of course, it is critical to have a solid ribbon of wood to the shear, and we have several new backlog control schemes available for the Planer and feed table to help this as well. This helps the lumber feed smoother on the table and from the nose of shear to the fence or guide. The angle of shear needs to be adjustable for wide and narrow products. Many people feel they need a powered shear, to help feed lumber to the table but In most cases they don’t. It is usually because the efficiency is very poor at other areas of the feed table. The first step would be to make sure the feed table is running at peak performance. If necessary, get a specialist in to take a look at it. At the high speeds feed tables run at, others may miss what the specialists at Cobra Technical Services will see. The best candidate for the Cobra powered shears for the Feed-table are mills who run green lumber or long lengths. When using a powered shear, it must be at 90 degrees of the table and run at a speed that insures the boards get over to and under the pineapple quickly. When using a Cobra powered shear you can chose either electric or hydraulic. Usually hydraulic is less expensive if the mill has hydraulic fluid close by.
The lead of the bed roll should be one that works best for the individual mill. All bed rolls for the Feed Table need to be the same diameter. They should be level with each other and set at the same degree angle. Although this may seem very basic, it is a common problem in most mills using a planer system. Cobra has used high speed cameras to study different bed rolls and pineapples. It was concluded that knurls on bed rolls act as brakes, and only slow down the entire system. The first step is to turn the bedroll around so that the spiral continues all the way to the fence. It is also important to replace the bed roll early due to consistent wear. The best thing to do is replace the bed rolls with Cobra Tech’s design. We now have a new design for equipment with the knurl machined into the spiral lead. This has made big differences in production! Cobra can insure that you have the right designed lead and surfaced rolls for your individual mill.
The best pineapple to use for your planer and feed table equipment is one specifically designed for the type of lumber and system in your mill. One reason the Cobra design works so well is the smooth transition from the lead to the knurl. Having this very smooth transition from the lead to the knurl makes the transition of the boards from the pineapples to the guide smooth, which gives you the ability to make things repeatable. One of the most important parts of increasing the production and up-time with the feed table is just that, MAKING IT REPEATABLE. The pineapple and bed rolls need to have the same spiral and lead. Imagine a national fine thread and a national course thread on a bolt. With one turn, each one travels different distances. The last thing we need is something working against you from the start. The Cobra design has improved production by 18% with some customers who did nothing else but install the new bed rolls and pineapples. Cobra Bed Rolls and Pineapples are the best in the industry, are made to fit any feed table, and are being used throughout the USA, South America, and Canada.
Its crucial tensioning pressures are correct to get the highest production. Most mills have too much pressure down on the pineapples. You should be able to lift the pineapple by using a 4ft 2×4 or pry bar. If there is too much pressure, mills need to run with a lot of backlog to help push the board under the pineapple. This also causes other inefficiency issues, like too much friction between the board and the guide causing problems accelerating the board forward. If there is to light of pressure the pineapples have a hard time overcoming the pressure from the backlog and slip on the lumber.
The positioning of the pineapple and short stock rolls on your feed table needs to be correct. Much of the time they are set too low which creates an unnecessary travel distance and decreases the ability to feed lumber at a repeatable rate. Being set too low causes the boards to hesitate on their way to the guide. The end result is lost time, efficiency, and overall throughput. Our positioning systems for planer tables operates each pineapple individually at speeds operators can achieve a position within a 1/8 or less, so they run gently on the boards not needing to climb or be forced up. The planer rolls need to be set close to the thin boards. Most the time planer feed rolls are set to low causing abuse to the planer and boards. This is also one big reason for breakup in the planer.
Throughout the years Cobra has applied just about every type of hydraulic motor. Many brands and different series of motors have gotten a bad reputation; not due to their design but by being misapplied from the start. This is a crucial area that must be carefully evaluated on your Planer feed table and maintained in a certain manner to keep up production after any improvements are made. Identify what motors are being used on your system. Find the hydraulic schematics if possible and check out how they are being run in series. Make note of any changes. The same things need to known about the HPU. Many of the Hydrostatic Transmission Pumps on drive systems are older models and are hard to keep in sync or to keep at a consistent speed. Instead of purchasing new pumps (which can be very expensive) Cobra has new electrical pump control devices and driver cards which make your current Newman system run like new. Reducing the amount of components in the system will also increase the efficacy of a hydraulic drive. It is amazing the amount of components that can be discarded when the system is designed right. Do you have a flow divider in your system? It is not necessary. This, along with many other components, just creates heat; causing inefficiencies and maintenance nightmares. These systems are famous for running too hot. If this is a problem with your planer system, Cobra can get this under control with a few helpful suggestions.
Maximizing Planer Table Efficiency
How to get the highest performance out of your planer
The set-up of the planer is very critical to get a good feed of lumber and a good finish. The planer should be able to feed one piece at a time and stay to size. If this isn’t happening it could be a number of issues. If we don’t cover your issue please give us a call. for a planer set up procedures
The planer tension should be set as low as possible without the rolls slipping on the lumber. It needs to provide a constant tension following the contrail of the lumber. In most cases, the pressure is set to high or gets knocked up by the incoming piece losing contact with the board. Please check all the wear area of the bearings, sleeves, and pins. If you have a lot of slop most likely the tensioning system is not even being used. Depending on what planer you have the tension values can be different.
The planer rolls need to be set close to the thin boards. Most the time planer feed rolls are set to low causing abuse to the planer and boards. This is also one big reason for breakup in the planer.
AC or DC drives work great, and we do recommend these when appropriate, however, they are not always affordable for the typical mill. Through the years Cobra Tech Inc. has successfully applied many high-efficiency hydraulic motors in planers and feed tables. We are able to apply this knowledge and choose the motors that will work best on your specific planer drives. Unless your planer runs at speeds slower than 800 FPM, we generally recommend hydraulic drives.
If your planer meets the requirements for using hydraulic drives we at Cobra Technical Services LLC can provide the system which will meet and exceed your needs, whether a new system or revamping an older one. In most cases, if the mill has an older electric drive, a conversion to hydraulic is much more affordable than a VDF drive system. If you already have hydraulic drives, it is also less expensive to stay with a hydraulic drive because you already have a power unit and other components that be reused. Revamping an older hydraulic drive carries many of its own considerations. Is the pump a variable displacement Hydrostatic Pump? Does it meet the displacement requirement for the speeds you plan on running? What type of pump controller and other devices drives the pump? What type of hydraulic motors are you currently using and how are they mounted? Are the motors run in series, if so, how? And, of course, the filtration and cooling systems must be taken into account.
If the pump is in a good running condition the next crucial component of the pump is the controller. There have been great advances when it comes to pump controllers and the devices which drive and control them. The controllers we use are adaptable to many of the older pumps, like Sundstrand, Eaton, and Denison. If the pump meets specs, there is no reason to purchase a new one.
Of course, just like the pump, the motors need to be the correct displacement. The motor also needs to be one engineered for this application. Many motors have been misapplied on drives, mounted wrong, or run ineffectively in a series, all of which has given hydraulic drives a bad name. Installed correctly, however, motors can produce great results and last a long time. When it comes to the motors, Cobra uses only one type. It is a highly efficient motor which has been proven to the industry to be the best.
The shaft size of the feed rolls also plays a role when it comes to our motor drives. Cobra uses a special b-lock coupling and mounts the motor directly to the shaft of the feed roll, therefore making it torque arm mounted. This gives the motors the ability to have the movement needed to ensure a long life. This can also allow you to get rid of many other components and really cleans up the planer.
Cobra Technical Services will survey your existing system and provide you with our recommendations for the most cost-effective solution for your planer mill upgrade.
Automatic Tensioning and Positioning Systems
One of the final stages of increasing the uptime and production is automating these systems. This achieves independent positioning of each roll to a predetermined set point with a touch of a button. The tensioning pressure is established in the same way. What is great about these systems is the PLC’s ability to memorize the settings for each product. Once you have determined the best parameters to get the smoothest operation and maximum production for each product, information is stored into the PLC and available at the push of a button when that product is being run the next time. This helps to minimize setup time and reduces variations in productivity. Automatic tensioning and positioning systems same time; where setting up before production or during production. Imagine, after any manual change to position or tension pressure due to a breakup or some other reason, all rolls and pressures go right back to the original set points. This automatically saves time and ensures that the planer is set to achieve maximum productivity.
There are two types of tensioning controls in the industry; a closed loop servo system with digital controls or a closed looped system with analog controls. We have experience with both types. We almost always recommend the analog system because it is easier to adjust and much more forgiving if things get out of adjustment. The bottom line better performance and more uptime.