The Machinery Directive 2006/42/EC came into force on
29th December 2009. Stewart Robinson, consultant
engineer at Pilz Automation Technology,believes the main
challenge it poses for end users is in the upgrading or
interlinking of machinery

In the current economic climate, many
industries no longer have the budgets to
invest in new plant and machinery. For
many, the only alternative is to upgrade or
optimise existing plant. However, it’s
important to remember that modifications
to existing machinery carried out after 29th
December 2009 might fall under the scope of
the new Machinery Directive.Many end
users are unaware that an existing
declaration of conformity is rendered invalid
if machinery undergoes a ‘significant change’.

It is important to exercise caution when
linking old and new machinery. The key
question here is whether it represents a
‘significant change’, because if it does, the
conformity assessment procedure will need
to be repeated. Generally, this will always be
the case when a machine’s performance data
is changed: if it is fitted with a second feed
device, for example. It’s important to check
every change in detail – ideally before the
change is made.

Extending the presumption of conformity
for EN 954-1 has not necessarily helped to
simplify application of the standards. Even if
EN 954-1 and EN ISO 13849-1 can be
applied in parallel until the end of 2011,
there are still some issues to bear in mind.

Many of the C standards listed under the
current Machinery Directive already refer to
EN ISO 13849-1 and EN 62061. In these
cases, application of EN 954-1 would no
longer enable presumption of conformity
directly, so machine manufacturers who wish
to adhere strictly to the C standards would
have to apply EN ISO 13849-1 or EN 60261.

In the case of interlinked machinery, the
position of the standards requires particular
attention. For example, on two stand-alone
presses built in 1998, manual loading is to be
replaced by a robot and the two presses are
to be interlinked.While the functional safety
of the presses is based on EN 954-1, the
robot must be designed in accordance with
EN ISO 13849-1 to comply with its C
standard. As a result, the interfaces between
the individual machines are based on
different standards, so cannot be assessed.

To represent the current state-of-the-art,
the end user would have to design the entire
plant in accordance with the new standard.

In practice this can prove difficult, partly
because the safety-related characteristic data
is unlikely to be available for the components
on the old presses and partly because the
cost of exchanging all the safety-related
components would be prohibitive.

In this case, the robot will have a
declaration of incorporation in accordance
with the Machinery Directive 2006/42/EC,
probably with reference to EN ISO 13849-1,
while the presses will have a declaration of
conformity in accordance with the
Machinery Directive 98/37/EC, with
reference to EN 954-1.

The interfaces and additional protective
equipment will require a risk assessment.

Functional safety must be categorised using
EN 954-1 and EN ISO 13849-1. By
categorising functional safety in accordance
with both standards, EN 954-1 can be
applied for the interface to the presses, while
EN ISO 13849-1 can be applied for the
interface to the robot. In this case, the
requirements of all the subassemblies can be
met. As a result, the requirements of the C
standard would be fulfilled on the robot, and
the end user would have established
compliance for the entire plant.

The CE marking process is carried out in
clearly defined steps. First establish whether
the planned upgrade constitutes a significant
change and whether stand-alone machines
are interlinked to form one complete system.

This is a given when two presses are interlinked
using a robot, so a declaration of
conformity must be produced for the
complete system.

A risk assessment must be carried out for
the robots and interfaces, to work out the
relevant safety measures. This will be used as
the basis for developing a safety concept,
which will describe all the mechanical,
electrical and other measures necessary for
plant safety. Regular function tests are also
required on the presses (i.e. the existing
machines which are already CE-certified).

Specify the safety requirements via the
safety design. Initially, the decision as to
which components to use in which type of
safety-related design is product-neutral. If
necessary, other risk reduction measures may
be defined, such as safety guards. This is
followed by system implementation, from
the selection and purchase of the required
components, through to training for
operating and maintenance staff.

The process is completed by verifying the
safety functions in order to demonstrate that
the safety measures that have been
implemented meet all the requirements. This
includes checking the operating manual, as
well as carrying out safety checks on all
safety-related components. Next are noise
level measurements and tests on the protective
earth conductor and insulation. If everything
is in order, the final report can be produced
and nothing else stands in the way of the
declaration of conformity.

Responsibility for machinery safety lies
with the end user who is also responsible if
he has commissioned a systems integrator to
upgrade a machine. If he doesn’t have the
necessary expertise, a third party should be
commissioned. Experts in safe automation of
plant and machinery can assist with upgrades,
assess results in terms of safety and, if necessary,
repeat the CE-marking process.

Pilz, for example, provides a range of
services and gives practical guidance on CE
marking, interpretation and correct
application of the standards listed under the
Machinery Directive.