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02
Drilling procedure
The material determines the drilling procedure:
g Solid building materials (high strength)
Rotational and impact drilling
g Cavity materials, light materials, boards
Rotational drilling
Assembly instructions
Create the drill hole
To ensure perfect functioning of the dowel system,
the stipulated bit diameter and drill depths must be
observed. Used, undersized bits impair functionality
and cause more assembly work that normally is not
financially viable.
Cleaning the borehole
Although often avoided, cleaning the borehole of bore
dust plays a decisive role Remains of bore dust have the
effect of a dirt layer between the dowel and the wall of
the borehole and considerably reduce the functionality.
Modern aids such as our assembly accessories program
facilitate this work.
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Technical information on dowel and anchor technique
Introduction
A range of influencing factors are to be taken into
account for the correct selection and dimensioning
of dowel anchoring. Engineering planning requires
substantial knowledge and a whole range of basic
information. Here, we want to provide a short overview
for all those that work in acquisition, dispatch, storage
and assembly of dowels. The following pages should
facilitate your choice in the future.
Material
The first question that a craftsman asks before
assembly is “what is the underground?”. As varied as
materials are, so varied are also the demands made of
dowels and anchor.
Here is a small survey of the normal materials.
Examples Properties Requirement of dowel
Solid materials Concrete, solid brick, natural stone, Often high resilience, Very suitable for fixings,
lime sand solid stone tight packing, no cavities as high splay forces and
low fixing depths are
possible
Cavitous Light top-hole brick, lime sand Various sizes of cav ty, various Long splay parts or mold-
materials perforated brick, cavity blocks made high compressive strength flush dowels required.
of light concrete Here the replacement with glue
mass often helps
Light materials Cavitous concrete (gas concrete), Low compressive strength, Long splay parts or positively
light concrete solid stone, many pores gripped dowels
gypsum boards, perhaps hard foam
Boards Gypsum boards, hardmasonite boards, Often low rigidity, Positively gripped dowels,
chipboards, wood wool light very low anchoring depths that anchors behind the board
construction boards
Common materials (from left to right):
Gas concrete (gas concrete) G, granite (natural stone),
Solid brick Mz, light top-hole brick LHLz, lime sand
perforated brick KSL (as brick and cavity block), light
concrete cavity block Hbl, light concrete solid brickV,
lime sand solid brick KSV, gypsum carton, concrete B,
in the background: expanded plastic slab
Applying the stipulated torque
There are stipulated tightening torques for every anchor;
these torques ensure ideal functioning of the anchor. A
tightening torque that is too high overloads threading
and increases the splay pressure on the underground
unnecessarily. Consequences: incorrect assembly and
safety risks.
Abbreviation for torque: M D
Why take border and axle distances
into account?
If the distance between dowels is too small so that the
load pins overlay, the underground surface that can
accept loads is reduced. Minimum distances must
therefore be observed.
In case of newer-generation dowel approvals, reduction
factors for the approved loads were introduced for
reduced axle distances.
Select dowel with sufficient clamping area
(usable length)
BTI offers a broad selection of clamping areas for all
dowel systems. Dowels with a short clamping area
reduce the anchoring depth and thereby the load
capacity of the underground. If the clamping area is not
fully required then the borehole must be bored deeper by
the respective measure.
Assembly techniques
Pre-plugging assembly
Before mounting the component to be fixed, the dowel is
set flush to the surface of the underground.
Drill depth: dowel setting depth+ 1 cm + any plaster
depth
Examples: Markant B, brass expansion dowel IMD,
cavity dowel GDK, concrete anchor E
push-through assembly
Here, the borehole must be made right through the part
to be fixed. The dowel is then plugged in.
Important: Consider the thickness of the part when
selecting the dowel.
Drill depth: dowel setting depth+ 1 cm + any plaster
depth + thickness of part
Example: anchor pin T-DN, insulation board holder DPH,
Simplex anchor BTI-SA
Spacing assembly
The part is assembled at a determined distance to the
surface of the underground at the projecting pin. The
dowel is also bend-stressed.
Pre-plug
assembly
Plug through
assembly
Spacing
assembly
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