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1. Important safety considerations
1.1 Safety tools
Machine tools for machining wood present a risk for the operator of such machines because of their high cutting speeds, their shape and sharpness, and if they are poorly designed, produced or incorrectly used.
Leitz tools are designed to the latest state of the art in tool technology and are made of specially selected tried and tested materials. They are quality tools ensuring:
" optimum protection against accident
" minimum pollution
" high performance and
" economy of use
Depending on the application, different tools are offered for:
" working with manual feed
" working with mechanical feed
Tools for working with manual feed are designed to achieve certain safety aims for manual feed in particular:
" to reduce the injuries on contact with a moving tool
" to reduce the kick back of the workpiece
With the aims of maximising the safety of woodworking machine tools whilst working with them and reducing the risk of injury to the user, tool manufacturers and timber associations in Germany have joined together to produce DIN standards and accident prevention regulations for implementation and by this they have made the runners for others regarding safety technique in Europe.
These proved safety regulations are a considerable basis of the European standard EN 847-1 "Machine-tools for the woodworking industry safety demands. Part I: Cutting and planing tools, circular sawblades."
It has been worked out by the help of the European tool producers and is valid in the countries of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Ireland, Italy, Luxembourg, the Netherlands, Norway, Portugal, Sweden, Switzerland, Spain and in the United Kingdom (U.K.).
In Germany the European standard has been adopted by the German standard committee DIN as German standard DIN EN 847-1.
The examining and certification board of the German trade association for the woodworking sector at request carries out examinations of the woodworking machine-tools in accordance with the DIN EN 847-1 and furthermore grants the well-known BG-TEST certificate for manual feed tools
The allowed limits and the examination conditions in its wording has become like the standard DIN EN 847-1.
The general safety specification for a tool defined by the DIN EN 847-1 includes:
" maximum RPM
" minimum balance quality
" minimum clamping length and knife thickness depending on the knife projection and cutting material
" knife clamping mechanism (form fitting or friction)
Leitz tools meet this European standard for safety, both in form and quality.
1.2 RPM limits
Tools with bores and tenon must be designed for speeds up to 12,000 RPM inclusive of a safety factor of 4 and for speeds of more than 12,000 RPM as safety factor of 2.25 applies. The proof can be effected by the help of calculation proceedings and by a centrifugal force examination.
1.3 Balancing quality according to ISO 1940-1
" Single part tools, tipped tools and bodies of tool sets: G 16
" Bodies for long planerheads for surface planers and combined surface planer thicknessers: G 6.3
" Tool sets: G 40
1.4 Tools for manual feed
" The limited gullet width "s" as defined when the regrinding area of both the cutter and, if present, the limitor, are exhausted is restricted and related to the large diameter of the tool.
" The cutter projection is related to the tool body or limitor and kick back speed as follows
- for non-circular shaped tools with a cutter projection of up to 1.1
mm: vR/vc < 0.25
- for circular tools cutter projections of up to 3 mm are allowed, but
at a reduced kick back ratio (DIN EN 847-1). The examination will be
effected by a kick back test.
1.5 Tools for mechanical feed
Mechanical feed is the term used for a feed mechanism for the workpiece or tool that is incorporated in the machine and with which the workpiece or machine element with the tool is held in position and guided mechanically during machining.
Tools for mechanical feed must comply with the general safety requirements as per DIN EN 847-1 in force.
There are, however, no limits in terms of cutter projection and gullet width.
The tools are marked with MEC and may only be used for working with mechanical feed.
1.6 Cutter clamping with composite tools
The knife clamping system must be secured by keyed elements to prevent the individual parts moving due to the effect of centrifugal forces. The design must ensure that the required minimum clamping length of the knives is observed. Friction clamped knives are allowed:
" for knives in tools for surface planers and planer thicknessers with knife widths greater than 150 mm
" for knives in tools (planer knives only, not profile or bevelling knives) for machines with mechanical feed
" for tools in chipping and chopping machines with mechanical feed
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