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== The Company: ==
'''Laitilan Metalli Laine''' Oy was established in 1973 for manufacturing circular sawmills. Since the company has manufactured and sold worldwide over 2000 sawmill units under LAIMET trade mark.
In the middle of 1990 LAIMET product range was extended with Screw Chippers. The screw chipper is a Finnish innovation and after Laitilan Metalli had acquired the holding of the production of this innovative product, the company has constantly developed and improved the product so that today LAIMET Screw Chipper range is widen to consist various different models suitable for many different purposes.
== Function principles of the screw chippers: ==
Function principle of a screw chipper is very simple and reliable. A conical screw blade when rotating pulls in the log and chips it at the same time.
The screw blade is attached on a fly wheel where rotating wings flip the chips out of the chipper.
There are different types of in-feed conveyors available for moving logs into the chipper in-put opening where the screw blade grabs the log and pulls it into the chipper. No additional in-feed device is required. As the screw blade rotates with a constant speed, also the chipping speed remains constant ensuring standard chip length and homogeneous, high quality chips unlike the chips produced with a drum- and disc chippers.
== Chipper models & options: ==
LAIMET Chippers can be categorized into two main types: '''High Speed and Low Speed''' -models. The rotation speed on a HS-model is 750 rpm and on LS-models 100-200 rpm. Both models have their own advantages.
HS-models are more productive due to that the rotation speed is higher, and while the wings on the fly wheel blow out the chips efficiently, no out-put conveyor for chips is needed. The blowing force through the chip out-put pipe can elevate the chips up to 5-6 m high. For the transmission on HS- models, multiple-V-belts are used, which are durable and reliable in industrial working environment.
LS-models on the other hand are quiet. Large heavy duty chippers are mostly LS-models as lower rotation speeds suit them better. The rotation speed is adjusted with a gear box allowing to use motors with less performance than on HS-models. LS-models discharge the chips beside the chipper due to a lower rotation speed and require a conveyor or other device to relocate the chips.
The chippers are driven either with a tractor or an electric motor. It is also possible to provide one with a diesel engine.
== Conveyors: ==
Laimet Low Speed Chippers can be provided with discharge conveyors of different belt widths and elevation angles. The discharge conveyor is possible to install so that it carries the chips to either side or to the back of the chipper. Material used on the belt conveyors is of resin resistant industrial rubber.
For in-feed conveyors, there are spiked roller conveyors as well as belt conveyors of various lengths to choose from, depending on use and other requirements.
Belt conveyors suit better for feeding slabs and sawmill waste. The chipper itself does not need any feeding device but the conveyor makes the feeding quicker and more efficient keeping the material flow to the chipper more constant. The conveyor speed can be adjusted with a transformer and on mobile models with hydraulics, and also has a reversing function.
== Re-Crusher: ==
LS-models can be equipped with a so-called '''Re-Crusher''' to ensure that the chips produced are homogeneous and of even size. The re-crusher has rotating hooked knives, which break only over sized pieces but not medium or small size chips. When producing chips for gasification the re-crusher ensures the quality of the chips. The Re-Crusher is available for 100-serie Low Speed models.
In the chassis of the chipper there is an integrated space for Re-Crusher as standard. In case the customer chooses to have one, the re-crusher parts; the hooked knives, their counter blades as well as a gear motor will be installed in this space.
== Chip size: ==
The chips sizes can be changed by choosing a screw blade with a different pitch. The screw blade is made of very resistant hard metal, Stellite and therefore a working life for this kind of blade is particularly long. When the hard-welded cutting surface is worn out, it can be refurbished at the manufacturer’s work shop. The cost of the repair is half of the price of a new corresponding screw blade.
== Advantages of screw blade chippers: ==
The most significant advantage is the high chip quality. Chips produced are even sized and splitter free with minimum quantities of sawdust and small particles.
The construction of the screw chipper is simple and therefore reliable, durable and long-lasting. There are very few parts that wear and need to be replaced. Furthermore the noise level of the Low Speed models is so low that they can even be used closed to dwellings.