Temporary fixation of Diamond Cutting and Coring … · Hilti Technical Anchor Handbook for further...

IACDS Anchors Temporary Fixing Diamond Equipment | BU DIA 2016 1 www.hilti.com

Temporary fixation of Diamond Cutting and Coring Equipment –

Recommendations and load considerations during operation

Dr. Martin Goedickemeier

Hilti AG - Schaan FL

IACDS Annual Meeting 2016 Munich


Content

Anchor Types for temporary fastening of Diamond Equipment

HKD drop-in anchors

HST stud anchors

HUS3 screw anchor

Failure modes of anchors

Concrete breakage

Anchor rupture

Slip

Sleeve rupture

Edge breakage

Load considerations for Diamond applications

Diamond tool «sharpness» determines load!

Diamond Coring

Track Saw

Wire Saw

Static vs. dynamic Load

Hilti Recommendations


General Remarks Regarding Anchor Safety

Disclaimer

Resistance of anchors depends highly on proper setting procedures and concrete conditions. All

indicated load values and safety considerations have to be considered in the actual application case.

The following calculations are to be regarded only as guidelines for safe applications and must not be

used separately or in a differnet context.

Hilti is not obligated for direct, indirect, incidental or consequential damages, losses or expenses in

connection with, or by reason of, the use of, or inability to use the products for any purpose. Implied

warranties of merchantability or fitness for a particular purpose are specifically excluded.

To safely anchor your equipment

Refer to the instruction manual of your equipment manufacturer. Length of e.g. railfeet and lever

action due to unfavorable design lead to high loads.

Consider special application conditions and application profiles. Cracked concrete and short edge

distances might make the use of a different anchor necessary.

Select the right anchor product for your specific case. When in doubt look for the help of an

engineer.

Create a safety concept for your operator safety by selecting proper anchoring products.

Hilti Technical Anchor Handbook for further reference (see your local Hilti homepage for your

own language)

https://www.hilti.ch/medias/sys_master/documents/hfa/9135227469854/Anchor_Fastening_Technolog

y_Manual_2014-09_Complete_Technical_information_ASSET_DOC_3880765.pdf


Anchor Types I: HKD and HKD-D drop-in

HKD: use in cracked and uncracked concrete extra safety


Proper Setting of HKD


HKD maximum loads


HKD edge distance

HKD-D M12x50

Edge distance: 175 mm

HKD M16x65



Anchor Types II: HST – stud anchor

HST: for use in cracked and uncracked concrete extra safety


HST maximum loads


Proper Setting of HST

HST M12


Torque: 60 NM

HST M16


Torque: 110 Nm


Anchor Types III: HUS3 – screw anchor

HUS3: Versatile, reusable anchor for temporary track saw fixation


HUS3 maximum loads


Proper Setting of HUS3

HUS3-H10x100


Torque: 45 Nm


HUS3 Setting and Re-Use

We recommend the use of an Hilti SIW

impact driver in concrete.

Use the gauge to determine HUS3 re-

usability.


Failure Modes of Anchors

1. Concrete break-out.

2. Anchor pull-away.

3. Shear rupture of steel.

3a. Tensile failure of anchor.

or pull-out (slipping)

4. Edge breakage.

Failure types 1-3 are typical failures of properly st anchors.

3a: Setting failures:

Steel rupture typically in over-torqued anchors.

Slip in not cleaned bore holes.

4 occurs when anchor is set too close to an edge


Diamond Tool “Sharpness”

= 0.3 … 0.8

Sharp

FN low @ given FC

= 0.1 … 0.2

Blunt

FN high @ given FC

FN

FC

FN

FC

FN is the pressing («normal») force on the segment.

FC is the cutting force on the diamond, it is given by tool power (torque!).

When machine power and rpm is constant FN grows when diamond is blunting.


Diamond coring loads require big anchors

Maximum normal force (FN) on a core bit

• high torque (MD) gear setting (low rpm)

• Small bit (r small)

• Blunting bit ( = 0.2)

Anchor load (FA) is defined by FN and

baseplate geometry. FN is the operator’s

pressing force.

Example (neglecting tool weight)

FA = 26 kN

MD: 50 Nm (Hilti DD 350, wrong gear)

: 0.2 (blunt bit)

r: 0.026 m (52 mm core bit)

𝐹𝑁 =𝑀𝐷

𝜇 ∙ 𝑟

𝐹𝐴 =𝐹𝑁 ∙ (𝑎 + 𝑏)

𝑏

Characteristic load of an HKD M20 («big anchor») is 26 kN.

This is reached under fairly normal conditions. Any smaller anchor is dangerous.

Small base plates increase the risk.

FN

FA

F1

a (25 cm)

b (15 cm)


Load characteristics Concept according ETA*

* European Technical Approval


Calculation example DD coring

Coring with Hilti DD 350 HKD M16x65

Anchor force

sharp bit kN

Anchor force

blunt bit kN

Recomm-

ended load

kN

Design

load kN

Characte-

ristic load

kN

52 mm bit

e-gear for 52 mm (28 Nm)

7.2 12.6 12.6

17.6 26.4

52 mm bit (wrong gear)


12.8 25.5 12.6 17.6

26.4

202 mm bit


5.3 10.6 12.6 17.6

26.4

DD 350 202 mm bit


6.3 12.6 12.6 17.6 26.4

Load recommendation can be easily exceeded, when using wrong gear settings

with small core bits together with blunt bits (wrong specification).

HKD M16x65 gives extra safety in this case, however with little safety margin.


Wall sawing: Redundancy of ≥2 anchors

𝐹𝑁 =𝑀𝐷

𝜇 ∙ 𝑟

Maximum pressing force (FN) on a saw blade

is determined by machine ( measure)

Anchor load (FA) is defined by FN and

rail foot geometry. Pressing force (FN) is

steered by the saw head.

𝐹𝐴 =𝐹𝑁 ∙ (𝑎 + 𝑏 + 𝑐)

𝑐+ 𝐹𝐺 ∙ 𝑑

Reducudancy of using minimum 2 anchors limits the risk in wall sawing.

Measurement exhibits FA of 6-11 kN. Hilti recommends HKD-D M12 or equivalent.

FG

FA

FN

a

b

c

d

r


Characteristic load of DS TS20-E track saw in

concrete is 6 – 8 kN, peak load at 11.3 kN

4 cm

12 cm

12 cm

2. Schnitt

-10000

-8000

-6000

-4000

-2000

0

2000

4000

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

Fdübel L

FdübelR

FA [N

]

left right

Forces measured at left (red) and right (green) anchor during application

left anchor‘s load right anchor‘s load


Static anchor loads in wire sawing are low

Static wire pulling force is 1 – 2 kN.

Maximum force is reached when wire blocks suddenly dynamic load:

a) relieved by wire rupture

b) Relieved by anchor breakage

Wire breaks at tensile loads ~ 10 kN depending on how long it is in use

(fatigue of wire or connector).

Dynamic loads on sudden wire blockage exceed anchor forces of 20 kN, if the

wire does not break.


Hilti recommends generally

Tool type Drop-in Screw Stud

DD Tools more than ~3 kW

DD 200 and up (torque**>50 Nm)

HKD M16x65

or equivalent

* *

DD Tools up to ~2.5 kW

up to DD 160 (<50 Nm)

HKD-D

M12x50

* *

Wall saw systems M12x50 HUS3 H10x100 HST M12

Wire saw systems M12x50 * *

Please consider

Not all anchors are usable in cracked or very weak concrete.

Inquire with your anchor specialist in case of doubt.

Inquire when working in critical conditions.

Use proper anchor setting procedures.

Consult the operation manual of your tool manufacturer. Manufacturers adapt their

recommendations based on experimental values and baseplate/rail foot geometries.

* These tools are usually fixed w. threaded rods HKD

** the torque of a tool defines the maximum load on the bit (not the power)

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Temporary fixation of Diamond Cutting and Coring … · Hilti Technical Anchor Handbook for further...

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