15.4
Subject to technical modifications without notice
DE-STA-CO
Building safe workholding systems
Safety
means paying attention to the smallest details. A hastily
assembled workholding system can result in a hazardous operator
environment. Hydraulic workholding is not a generic technique where
most anything will work, nor is there one right or best answer for all
situations. Each application is different and can be approached in
many different ways. Because of this versatility, there is no rule-of-
thumb to follow to guarantee safety. A careful balance of knowledge,
fixture design and common sense are key to avoiding injuries.
Plan
your fixture installation with operator safety in mind. By nature,
most clamping devices have pinch points. Many times the fixture can
be designed to shield the operator from a pinching hazard. Often the
placement of the clamping device in the fixture can minimize the gap
between the clamp and the workpiece, thus reducing or eliminating
the pinch point. Perhaps the clamping control valve or switch can be
located such that the operator
cannot reach the fixture
and the control at the same
time. Dual palm buttons on
electrically-actuated systems
serve the same purpose.
Do not
require the operator
to hold the workpiece in position during the clamping operation. Make
sure that the workpiece is self-supporting and self-locating so that
operator hands are out of danger when the hydraulic system is
actuated. Often a simple spring plunger is all that is necessary.
The
lowest
pressure rating
of any
component in the clamping system
sets the
maximum
pressure rating
for the entire system.
Most
hydraulic
workholding
components are rated at 5,000
PSI maximum. However, some components are rated at less than 5,000
PSI. The maximum pressure is listed on each product page of this
catalog.
Never exceed this rating
.
Just having a clamp that is rated
at 5,000 PSI is not enough. Every
hose, fitting, valve, adapter and
tube exposed to pressure must be
rated at or above the maximum
hydraulic system pressure. Most
“hardware store” fittings are intended only for low pressure
plumbing.
Never use water pipe fittings or copper tubing and brass
fittings for hydraulic service.
Use
proper
tools
when
bending tubing, and maintain
proper minimum bend radii for
hoses and tubing. If a hose or
tube is ever kinked, replace it.
Don’t risk a rupture. Fluid
escaping under high pressure is dangerous. The resulting loss in
pressure could release the workpiece from the fixture and cause
serious injury and equipment damage by being ejected from the
machine or breaking tooling.
Tubing and hoses do flex when
pressurized. Allow for that
movement by supporting the
fluid lines away from surfaces
which could abrade the surface
and eventually cause damage.
Avoid straight lengths of hose and tubing. A bend will allow for this
deflection without putting too much stress on the line.
Even if proper hydraulic tubing
and fittings are specified, be
sure to protect them from
abuse. Components damaged
from abrasion or accidental
dropping of a workpiece will no
longer have the strength and
safety of the original design.
Use
proper mounting hardware
when
installing
workholding
clamps and other components.
Always
use
the
largest
bolt
available to fit in the mounting
hole.
In
many
cases,
the
recommended cap screw or thread is specified on the product page
of this catalog. Sometimes the mounting hardware is included with
the component. Always use supplied hardware.
Safety means
paying attention
to the
smallest details.
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15_StrongHold.qxp:15_DES_StrongHold-1-14.indd 1/2/08 9:03 AM Page 15.4