SCOPE OF STANDARD
The European standard EN 847-1:1997 sets the safety prescriptions concerning mills and blades of disk saws.
The prescriptions concern:
- mechanical features to guarantee that these tools resist to strains if used correctly,
- geometrical features, especially as far as the tools used for manual advancement are concerned, to guarantee low refusal speeds and
- reduced damage in case of contact.
JURIDICAL VALIDITY OF THE STANDARD
The juridical effects of the standard differ according to the juridical situation in various countries. They range from being compulsory when the standard or certain main features are specifically mentioned by a law, for example in:
- Germany where the limitation to 1.1 mm for manual tools has been in force since the Eighties,
- U.K where the purchase of new tools complying with the standard is compulsory besides the replacement of old ones by 2003,
- Switzerland where after 30.06.1999 no non-conforming tools can be purchased and all non-conforming ones must be replaced in any case by 2005, to non-compulsory effects but legal effects in other countries where,
INNOVATIVE CONTENTS OF STANDARD
As far as mechanical advancement tools with MEC mark are concerned, the standard establishes only construction features in terms of best state-of-art, already known and tested.
The most important news regard the geometrical features that allow tools for manual advancement with MAN mark:
- to have low refusal speeds and
- to reduce by over 90% the seriousness of injuries in case of contact with operators' hands and fingers.
The limitation of the projection of tools, also called limitation of cutting depth, is the most qualifying feature of MAN tools according to EN 847-1:1997.
With a limitation of:
- 1.1mm for tools that do not have a round shape and
- a maximum of 3 mm for tools with a round shape (according to refusal speed) and with specific design of the geometrical shape, the advancement is easier to control and in case of contact with the tool, there are no mutilating effects but generally only surface injuries.
LIMITS
Unfortunately the cutting depth limit can be applied only to tools used
at low advancement speed, such as those achieved manually. In addition,
the cutting depth limit cannot be applied to disk saw blades.
PROTECTIVE DEVICES OF MACHINES
The tools are not an alternative to the use of protective devices and
to safe working procedures, they should rather be considered a further
step towards the maximum reduction of risks.
MACHINES ON WHICH TOOLS CAN BE USED
The new MAN tools must be used on:
- manual advancement milling cutters, such as toupies and
- one-side tenoner with manual advancement carriage.
MARKING
The tools cannot be provided with CE mark, however their compliance with the standard must be declared by the manufacturer in brochures and instruction sheets.
Moreover, the tools must also be marked as follows:
- trade mark or name of manufacturer or supplier,
- speed range (MAN) or maximum speed (MEC) and
- MAN or MEC wording if for manual or mechanical advancement
- standard dimensions, i.e. max. outer diameter x hole diameter x max. cutting height.
All tools with mechanically fixed elements must be submitted to type testing to assess mechanical resistance of fixed parts. The test is performed by rotating the tools generally at double the speed rating to assess that any movement is less than what is prescribed by standards.
MAN tools must be submitted to a refusal test performed with specific equipment to assess that the refusal speed remains within the limits prescribed by the standard.
Dott. Ing. Attilio Griner
Acimall, Milan