Hitachi WH 14DSL Manual

CORDLESS IMPACT DRIVER
WH 14DSL
CORDLESS IMPACT WRENCH
WR 14DSL
WH 14DSL
WR 14DSL
Feb. 2008
LIST Nos. WH 14DSL: G894
WR 14DSL: G895
MODELS
WH 14DSL
WR 14DSL
W

REMARK:
Throughout this TECHNICAL DATAAND SERVICE MANUAL, a symbol(s) is(are) used in the
place of company name(s) and model name(s) of our competitor(s). The symbol(s) utilized here
is(are) as follows:
WH 14DSL
Competitors
Symbols Utilized Company Name Model Name
P MAKITA BTD130F
WR 14DSL
Competitors
Symbols Utilized Company Name Model Name
None --

CONTENTS
Page
1. PRODUCT NAME ---------------------------------------------------------------------------------------------------------- 1
2. MARKETING OBJECTIVE ---------------------------------------------------------------------------------------------- 1
3. APPLICATIONS ------------------------------------------------------------------------------------------------------------ 1
4. STANDARD EQUIPMENT ----------------------------------------------------------------------------------------------- 1
5. SELLING POINTS --------------------------------------------------------------------------------------------------------- 2
5-1. Selling Point Descriptions ---------------------------------------------------------------------------------------- 4
6. SPECIFICATIONS --------------------------------------------------------------------------------------------------------- 8
6-1. Specifications ---------------------------------------------------------------------------------------------------- 8
6-2. Optional Accessories ------------------------------------------------------------------------------------------- 9
7. COMPARISONS WITH SIMILAR PRODUCTS ---------------------------------------------------------------------12
7-1. Specification Comparisons (Cordless impact driver) ---------------------------------------------------12
7-2. Specification Comparisons (Cordless impact wrench) -------------------------------------------------13
7-3. Tightening Torque------------------------------------------------------------------------------------------------14
7-4. Tightening Time --------------------------------------------------------------------------------------------------18
7-5. Number of Screws or Bolts Driven --------------------------------------------------------------------------19
8. PRECAUTIONS IN SALES PROMOTION --------------------------------------------------------------------------20
8-1. Safety Instructions -------------------------------------------------------------------------------------------------20
8-2. Tightening Torque Inspection Prior to Operation ----------------------------------------------------------23
8-3. Tightening Torque Variation--------------------------------------------------------------------------------------23
8-4. Suggestions and Precautions for the Efficient Use of the Charger ----------------------------------24
9. OTHER PRECAUTIONS--------------------------------------------------------------------------------------------------25
10. REPAIR GUIDE------------------------------------------------------------------------------------------------------------26
10-1. Precautions in Disassembly and Reassembly------------------------------------------------------------26
10-2. Precautions in Disassembly and Reassembly of Battery Charger-----------------------------------41
11. STANDARD REPAIR TIME (UNIT) SCHEDULES ---------------------------------------------------------------42
Assembly Diagram for WH 14DSL
Assembly Diagram for WR 14DSL

-1-
1. PRODUCT NAME
Hitachi Cordless Impact Driver, Model WH 14DSL
Hitachi Cordless Impact Wrench, Model WR 14DSL
2. MARKETING OBJECTIVE
The new Models WH 14DSL and WR 14DSL are the compact-type cordless impact driver/wrench
developed to reinforce our 14.4-V product lines and also to meet the market demands. These
new models have powerful tightening torque thanks to the optimized impact timing, hook and
protector (standard accessories). In addition, each of these new models is equipped with a slide-
type lithium-ion battery to materialize the compact body, built-in LED light, and convenient
remaining battery indicator. Thus the Models WH 14DSL and WR 14DSL are excellent in
performance, user-friendliness and operability.
3. APPLICATIONS
• Tightening/loosening of small screws, tapping screws, wood screws, bolts, nuts, etc.
• Drilling into wood and various other materials (with use of optional accessory drill chuck
adapter).
[Applicable Markets]
• Wood-product assembly: Tightening/loosening of wood screws
• Construction industry: Assembly of scaffolding, roofing, aluminum sashes, fencing, etc.; removal
of plastic cones from concrete forms, mounting/removal of form ties; drilling into the wood
frames of concrete forms, etc.
• Manufacturing industry: Assembly work for automobiles, rolling stock, shipbuilding, agricultural
machinery and tools, industrial machines, steel furniture, etc.
• Utility industry: Assembly and installation of electric equipment, plumbing facilities, air
conditioning (duct assembly etc.), sanitary fixtures and various other facilities.
• Service industry: General repair work; installation of advertising aids, automobile repair,
assembly of garages, carports and storage sheds, etc.
• Various other assembly, construction or repair facilities
4. STANDARD EQUIPMENT
Models WH 14DSL/WR 14DSL
(1) 2LSCK specification: Two BSL 1430 batteries (Li-ion, capacity 3.0 Ah), battery cover,
UC 18YRSL charger and case
(2) NN specification: Only the main body

-2-
5. SELLING POINTS
Powerful tightening torque
Equipped with lightweight and high-capacity (3.0 Ah) lithium-ion battery
Switchable impact rate between save mode and power mode
Model WH 14DSL
Slide type lithium-ion battery
Type BSL 1430 (Capacity: 3.0 Ah)
The Type BSL 1430 lithium-ion battery is equipped with the
overdischarge protection circuit, overcurrent protection circuit
and voltage monitoring circuit for each cell for longer service
life and safety.
• The Model WH 14DSL is equipped with the overdischarge
and overcurrent protection circuit to prevent overdischarge
(overuse) of the battery.
• The Type BSL 1430 lithium-ion battery is equipped with the
voltage monitoring circuit for each cell to prevent overcharge
of the battery.
Charger specifically designed
for slide type lithium-ion
batteries
Model UC 18YRSL Latch
(on both sides)
(2) Remove. (1) Push.
Battery
Tightening torque 145 N•m
(1,480 kgf•cm) Compact body: 145 mm in overall length
• Convenient for continuous operation in narrow places
Easy-to-grip thin handle
New type of hook
Switchable impact rate
between save mode and
power mode
• Suitable for tightening
machine screws
Built-in white LED light
Tool tip is structured without
screws. The protector is a
standard accessory.
Switch and monitor panel
• Remaining battery indicator lamp
• Remaining battery indicator switch
• Light switch

-3-
Latch
(on both sides)
(2) Remove. (1) Push.
Battery
Model WR 14DSL
Slide type lithium-ion battery
Type BSL 1430 (Capacity: 3.0 Ah)
The Type BSL 1430 lithium-ion battery is equipped with the
overdischarge protection circuit, overcurrent protection circuit
and voltage monitoring circuit for each cell for longer service
life and safety.
• The Model WR 14DSL is equipped with the overdischarge
and overcurrent protection circuit to prevent overdischarge
(overuse) of the battery.
• The Type BSL 1430 lithium-ion battery is equipped with the
voltage monitoring circuit for each cell to prevent overcharge
of the battery.
Tightening torque 165 N•m
(1,685 kgf•cm) Compact body: 152 mm in overall length
• Convenient for continuous operation in narrow places
Easy-to-grip thin handle
New type of hook
Switchable impact rate
between save mode and
power mode
• Suitable for tightening
small-diameter bolts
Built-in white LED light
Tool tip is structured without
screws. The protector is a
standard accessory.
Switch and monitor panel
• Remaining battery indicator lamp
• Remaining battery indicator switch
• Light switch
Charger specifically designed
for slide type lithium-ion
batteries
Model UC 18YRSL

-4-
5-1. Selling Point Descriptions
Selling points of the Models WH 14DSL and WR 14DSL:
(1) Equipped with the lightweight and high-capacity (3.0 Ah) lithium-ion battery
• Thanks to the adoption of the lithium-ion batteries, the Models WH 14DSL and WR 14DSL are
substantially lighter than the current models equipped with Ni-MH batteries.
BSL 1430 EB 1430H
Voltage (V) 14.4 14.4
Capacity (Ah) 3.0 3.0
Weight (g) 520 910
The Type BSL 1430 lithium-ion battery is equipped with the overdischarge protection circuit,
overload protection circuit, and voltage monitoring circuit for each cell to prevent shortening of
the battery life due to overdischarge (overuse) or overcharge (excessive charging) of the
battery.
The number of charging/discharging is about 1,500.
Precautions for use of the Type BSL 1430 lithium-ion battery
The Type BSL 1430 lithium-ion battery is equipped with a protective function that
automatically stops output to extend the battery life. The motor may stop automatically in
either of the following case(a)or (b) even if the switch is depressed continuously during
operation. This is because the protective function is activated. The battery is not faulty.
(a)The motor automatically stops when the remaining battery level is low (when the battery
voltage is decreased to about 8 V (Type BSL 1430)). Charge the battery immediately in
such case.
(b)The motor may stop if the Model WH 14DSL/WR 14DSL is overloaded. In such case,
release the switch and eliminate the cause of the overload problem. Then the Model
WH 14DSL/WR 14DSL will be operable.
Please instruct the customers on the above precautions.
(2) Switchable impact rate between save mode and power mode
The impact rate is switchable between two modes (save mode and power mode) according to
applications. Put the Model WH 14DSL/WR 14DSL into the save mode for tightening machine
screws into soft materials or put into the power mode for tightening long screws into hard
materials. These models are very convenient because the impact rate can be adjusted
according to the working conditions.
* Precautions for use in the save mode
If the Model WH 14DSL/WR 14DSL is operated continuously in the save mode, the temperature
of the electronic circuit modules in the switch may rise and it may result in burnout.
Tightening in the save mode*
•Suitable for light load operation
such as retightening machine
screws!
Tightening in the power mode
•Suitable for heavy load operation
such as tightening long screws and
bolts!
Switchable

-5-
(3) Remaining battery indicator
Each of the Models WH 14DSL and WR 14DSL is equipped with the remaining battery
indicator. The battery remaining power can be checked just by pressing the remaining battery
indicator switch.
(4) Built-in white LED light
Each of the Models WH 14DSL and WR 14DSL incorporates the white LED light. It is very
convenient for operation in dark places.
State of
lamp Battery remaining power
The battery remaining power
is enough (about 60% or
higher).
The battery remaining power
is a half.
The battery remaining power
is nearly empty (about 30% or
lower). Recharge the battery
immediately.
NOTE:
• The remaining battery indicator
lamp lights only after the battery
has been installed in the tool and
the trigger switch has been pulled
once.
• The indicator lamps of the high/lo
w
selector switch and the
single/continuous selector switch
go off immediately even though the
trigger switch is pulled when the
battery remaining power is nearly
empty and the protection function
is activated. It is not faulty.
NOTE:
• To prevent the battery power consumption
caused by forgetting to turn off the LED light,
the light goes off automatically in about 15
minutes.
• The white LED light is lighted by pressing the
light switch only after the battery has been
installed in the tool and the trigger switch has
been pulled once.
Remaining battery indicator switch
Remaining battery indicator lamp
Light switch

-6-
Selling points of the Model WH 14DSL
•High tightening speed and powerful torque: 145 N•m (1480 kgf•cm, 1280 in-lbs.)
(1) Tightening time comparison
Figure 1 shows the time required for tightening a wood screw (5.3 mm dia. x 120 mm
length) into a lauan workpiece.
•WH 14DSL: 7 % higher than P
Fig. 1 Tightening time comparison
* Tightening time may vary depending on hardness of the workpiece, ambient temperature,
characteristics of the battery, etc.
(2) Tightening torque comparison
Figure 2 shows the torque required
for tightening an M14 high-strength
tension bolt in 3 seconds with a
hexagon socket (40 mm long).
•WH 14DSL: 8 % higher than P
Fig. 2 Tightening torque comparison

-7-
Selling points of the Model WR 14DSL
•Powerful tightening torque: 165 N•m (1680 kgf•cm, 1460 in-lbs.)
(1) Tightening torque
Figure 3 shows the torque required for tightening an M16 F10T bolt in 3 seconds with a
hexagon socket (40 mm long).
Fig. 3
* The data above are intended for reference purposes only because actual tightening
torque will vary depending on tightening conditions.
Tightening torque

-8-
6. SPECIFICATIONS
6-1. Specifications
Models WH 14DSL/WR 14DSL
Model
Item Cordless impact driver
WH 14DSL Cordless impact wrench WR 14DSL
Capacity Small screw M4 to M8 (5/32" to 5/16")*1
Ordinary bolt M5 to M14 (3/16" to 9/16")
High-strength bolt M5 to M12 (3/16" to 15/32")
Ordinary bolt M6 to M16 (1/4" to 5/8")
High-strength bolt M6 to M12
(1/4" to 15/32")
Power mode 145 N•m (1480 kgf•cm,1280 in-lbs.)*2165 N•m (1680 kgf•cm, 1460 in-lbs.)*3
Tightening
torque Save mode 80 N•m (815 kgf•cm, 710 in-lbs.)*290 N•m (920 kgf•cm, 800 in-lbs.)*3
Tip condition 6.35 mm (1/4”) bit holder 12.7 mm (1/2”) square drive
Type of motor Fan cooled rare-earth magnet motor
Enclosure
Main body: Polyamide resin + elastomer ------ Housing
Aluminum alloy die casting -------- Hammer case
Elastomer ----------------------------Protector
Storage battery: Polycarbonate resin (black)
Charger: ABS resin (black)
Type of switch Trigger switch with forward/reverse changeover pushing button (with brake)
Handle configuration T-type
No-load rotational speed 0 to 2,600/min (Power mode) / 0 to 2,000/min (Save mode)
Impact rate 0 to 3,200/min (Power mode) / 0 to 2,400/min (Save mode)
Main body 1.4 kg (3.1 lbs.) (Includes battery)*41.5 kg (3.3 lbs.) (Includes battery)*4
Weight Battery 0.5 kg (1.1 lbs.)
Overall length x height 145 mm (5-45/64”) x 235 mm (9-1/4”) 152 mm (5-63/64”) x 235 mm (9-1/4”)
Center height 29 mm (1-9/64”)
Battery
(Type BSL 1430)
Sealed cylindrical Li-ion battery
Nominal voltage: DC 14.4 V
Nominal life: Charging/discharging approximately 1,500 cycles
(in the case of the Model UC 18YRSL)
Nominal capacity: 3.0Ah
Charger
(Model UC 18YRSL)
Overcharge protection system:
(1) Battery voltage detection (- V system)
Battery temperature detection (dT/dt system)
(2) Battery surface temperature detection (thermostat or thermistor)
(3) 120-minute timer
(4) Stop current detection
Power input: 90 W
Charging time:Approx. 45 minutes [for Type BSL1430 battery at 20°C (68°F)]
Operable ambient temperature range: 0°C to 40°C (32°F to 104°F)
The maximum allowable temperature of the Type BSL 1430 battery is 50°C (122°F).
Indication method of battery charging function
*1: M3 (1/8") tapping screws and wood screws are the smallest screws that can be tightened.
*2: This torque is based on tightening an M12 (9/16") bolt (strength grade: 12.9) for 3 seconds with a hexagon socket.
*3: This torque is based on tightening an M16 (5/8") bolt (F10T) for 3 seconds with a hexagon socket.
*4: Main body does not include accessory tools and hook (hexagonal bit etc.).

-9-
6-2. Optional Accessories
(1) Optional accessories for the Model WH 14DSL
•Plus driver bit
•Hexagon socket
Part name Stamped figure L
(mm) B (mm) Code No.
5 mm hexagon socket 8 65 (2-9/16”) 8 (5/16”) 996177
6 mm hexagon socket 10 65 (2-9/16”) 10 (3/8”) 985329
5/16” hexagon socket 12 65 (2-9/16”) 12 (15/32”) 996178
8 mm hexagon socket 13 65 (2-9/16”) 13 (1/2”) 996179
10 mm hexagon socket (small type) 14 65 (2-9/16”) 14 (9/16”) 996180
10 mm hexagon socket 16 65 (2-9/16”) 16 (5/8”) 996181
10 mm hexagon socket 17 65 (2-9/16”) 17 (21/32”) 996182
1/2” hexagon long socket 21 166 (6-17/32”) 21 (53/64”) 996197
•Drill chuck adaptor set (Code No. 321823)
The drill chuck adaptor set permits mounting of various types of locally-available drill bits for a
variety of drilling operations.
Bit No. Code No.
No. 2 992671
No. 3 992672
50 mm (2”)
Stamped figures
BL

-10-
(2) Optional accessories for the Model WR 14DSL
•Dimensions and applicable bolts for each hexagon socket
•Dimensions and applicable bolts for each long socket
Shape B Shape DShape C
LSq
HL1L1L1
LL
Shape B Shape D
L
Sq
HL1L1L2
L2L
D1(dia.)
D1(dia.)

-11-
•Bit adaptor (Code No. 991476)
•Extension bar [Overall length 100 mm (3-15/16") ] (Code No. 873633)
•Universal joint (Code No. 992610)
•Socket ass'y for duct
•EW-14R corner attachment
6.35 mm (1/4”)
13.5 mm dia.
(17/32”)
45 mm (1-25/32”) 12.7 mm (1/2”) Part name Overall length
(mm) Code No.
45 (1-25/32”) 983005
Plus hd.
driver bit
No. 2 65 (2-9/16”) 983006
45 (1-25/32”) 983010
Plus hd.
driver bit
No. 3 65 (2-9/16”) 983011
Dihedral width of
applicable bolts Code No.
12 (15/32”) 993658
13 (1/2”) 992613
14 (9/16”) 992615

-12-
7. COMPARISONS WITH SIMILAR PRODUCTS
7-1. Specification Comparisons (Cordless impact driver)
Maker HITACHI
Item Model WH 14DSL WH 14DL P
Small screw M 4 to M 8
(5/32" to 5/16") *1 M 4 to M 10
(5/32" to 3/8") *1 M 4 to M 8 (5/32" to 5/16")
Ordinary bolt M 5 to M 14
(3/16" to 9/16") M 6 to M 14 (1/4" to 9/16") M 5 to M 14 (3/16" to 9/16")
Capacity
High-strength bolt M 5 to M 12
(3/16" to 15/32") M 6 to M 12 (1/4" to 15/32") M 5 to M 12 (3/16" to 15/32")
Power mode 145
(1,480 kgf•cm,
1,280 in-lbs.)
140
(1,430 kgf•cm,
1,240 in-lbs.)
140
(1,430 kgf•cm,
1,240 in-lbs.)
Max. tightening
torque*2
Save mode
N•m80
(815 kgf•cm,
710 in-lbs.)
75
(765 kgf•cm,
670 in-lbs.) -
Power mode 0 to 2,600 0 to 2,600 0 to 2,400
No-load rotational
speed Save mode min-1 0 to 2,000 0 to 2,000 -
Power mode 0 to 3,200 0 to 3,200 0 to 3,200
Impact rate Save mode min-1 0 to 2,400 0 to 2,400 -
Catalog specifications
Main body weight*3 kg 1.4 (3.1 lbs.) 1.5 (3.3 lbs.) 1.4 (3.1 lbs.)
Max. tightening
torque*2 Power mode N•m153
(1,560 kgf•cm,
1,355 in-lbs.)
150
(1,530 kgf•cm,
1,330 in-lbs.)
141
(1,440 kgf•cm,
1,250 in-lbs.)
Power mode 0 to 2,580 0 to 2,610 0 to 2,420
No-load rotational
speed Save mode min-1 0 to 1,960 0 to 2,040 -
Power mode 0 to 2,790 0 to 3,190 0 to 3,160
Impact rate Save mode min-1 0 to 2,210 0 to 2,490 -
Overall length x height mm 145 x 235
(5-45/64" x 9-1/4") 162 x 236 (6-3/8" x 9-19/64") 146 x 235 (5-3/4" x 9-1/4")
Center height mm 29 (1-9/64") 27 (1-1/16") 29 (1-9/64")
Main body weight *3 kg 1.49 (3.3 lbs.) 1.58 (3.5 lbs.) 1.45 (3.2 lbs.)
Measured figures
No-load sound pressure level dB(A) 70 72 73
Remaining battery indicator Provided Not provided Not provided
LED light Provided Provided Provided
Type of switch Variable speed
switch with
forward/reverse
changeover lever
Variable speed
switch with
forward/reverse
changeover lever
Variable speed
switch with
forward/reverse
changeover lever
Type of motor DC magnet DC magnet DC magnet
Voltage V 14.4 14.4 14.4
Type BSL 1430 BCL 1430 BL1430
Nominal capacity Ah 3.0 3.0 3.0
Nominal voltage V 14.4 14.4 14.4
Battery
Ambient temperature °C0 to 40 0 to 40 -
Model UC 18YRSL UC 18YRL DC 18SC
Nominal input capacity VA 90 95 -
Charger
Recharging voltage V 7.2 to 18 7.2 to 18 7.2 to 18
Standard accessories •Plastic tool case
•Charger
(UC 18YRSL)
•Rechargeablebattery
•Battery cover
•Plastic tool case
•Charger
(UC 18YRL)
•Rechargeablebattery
•Plastic tool case
•Charger
(DC 18SC)
•Rechargeablebattery
*1: M3 (1/8") tapping screws and wood screws are the smallest screws that can be tightened.
*2: Max. tightening torque is based on tightening an M14 (9/16") bolt (strength grade: 12.9) for 3 seconds with a
hexagon socket.
*3: Main body weight does not include accessory tools and hook (hexagon bit etc.).

-13-
7-2. Specification Comparisons (Cordless impact wrench)
Maker HITACHI
Item Model WR 14DSL WR 14DL
Ordinary bolt M 6 to M 16
(1/4" to 5/8") M 10 to M 16 (3/8" to 5/8")
Capacity
High-strength bolt M 6 to M 12
(1/4" to 15/32") M 8 to M 14 (5/16" to 9/16")
Power mode 165
(1,680 kgf•cm,
1,460 in-lbs.)
200
(2,040 kgf•cm,
1,770 in-lbs.)
Max. tightening
torque*1
Save mode
N•m90
(920 kgf•cm,
800 in-lbs.)
110
(1,120 kgf•cm,
980 in-lbs.)
Power mode 0 to 2,600 0 to 2,600
No-load rotational
speed Save mode min-1 0 to 2,000 0 to 2,000
Power mode 0 to 3,200 0 to 3,200
Impact rate Save mode min-1 0 to 2,400 0 to 2,400
Catalog specifications
Main body weight*2 kg 1.5 (3.3 lbs.) 1.5 (3.3 lbs.)
Max. tightening
torque*1 Power mode N•m170
(1,735 kgf•cm,
1,505 in-lbs.)
232
(2,370 kgf•cm,
2,055 in-lbs.)
Power mode 0 to 2,580 0 to 2,610
No-load rotational
speed Save mode min-1 0 to 1,960 0 to 2,040
Power mode 0 to 2,790 0 to 3,190
Impact rate Save mode min-1 0 to 2,210 0 to 2,490
Overall length x height mm 152 x 235
(5-63/64" x 9-1/4") 167 x 236 (6-37/64" x 9-19/64")
Center height mm 29 (1-9/64") 27 (1-1/16")
Main body weight*2 kg 1.52 (3.4 lbs.) 1.59 (3.5 lbs.)
Measured figures
No-load sound pressure level dB(A) 70 72
Remaining battery indicator Provided Not provided
LED light Provided Provided
Type of switch Variable speed switch with
forward/reverse
changeover lever
Variable speed switch with
forward/reverse
changeover lever
Type of motor DC magnet DC magnet
Voltage V 14.4 14.4
Type BSL 1430 BCL 1430
Nominal capacity Ah 3.0 3.0
Nominal voltage V 14.4 14.4
Battery
Ambient temperature °C0 to 40 0 to 40
Model UC 18YRSL UC 18YRL
Nominal input capacity VA 90 95
Charger
Recharging voltage V 7.2 to 18 7.2 to 18
Standard accessories
•Plastic tool case
•Charger
(UC 18YRSL)
•Rechargeable battery
•Battery cover
•Plastic tool case
•Charger
(UC 18YRL)
•Rechargeable battery
*1: Max. tightening torque is based on tightening an M16 (5/8") bolt (F10T) for 3 seconds with a hexagon socket.
*2: Main body weight does not include accessory tools and hook (hexagon bit etc.).

-14-
7-3. Tightening Torque
7-3-1. Tightening torque characteristic comparisons
(1) Impact driver (14.4 V)
(2) Impact wrench (14.4 V)
Test conditions
Bolt: M14 x 50 mm, high-strength bolt
Steel plate: SS34P
Thickness 25 mm
Accessory tool: Hexagon socket
(length: 40 mm,
width across flat: 19 mm)
Test conditions
Bolt: M16 x 55 mm (5/8" x 2-5/32") (F10T)
Steel plate: Mild steel
Thickness 25 mm
Accessory tool: Hexagon socket ass'y

-15-
7-3-2. Screw diameter and appropriate tightening torque
Generally speaking, the appropriate tightening torque for a screw can be determined by the
strength grade of the screw and the material tightened. Tables 1 and 2, and Fig. 4 below list data
relative to the strength grade of various screws and the appropriate tightening torque. For further
reference, appropriate tightening torque is calculated with the following formula. Study and use
this formula for accurate selection of tightening torque.
T=k•d•p
T: Appropriate tightening torque (kgf•cm)
d: Nominal diameter of thread (mm)
p: Recommended axial tightening force to be applied to the screw (kgf)
p = rated axial stress (kgf/mm2) x 0.8 x Effective sectional area of thread (mm2)
k: Torque coefficient (0.17)
•Strength grade and rated axial stress of thread
Table 1
Strength grade 4.8 6.8 8.8 12.9
Rated axial stress (kgf/mm2) 29.1 43.7 58.2 95
Material Mild steel Alloy steel including Ni, Mn, Cr, etc.
Heat treatment Not processed Processed: Hard material
•Diameter and effective sectional area of thread
Table 2
Kind of thread x pitch M5 x 0.8 mm
(3/16") M6 x 1 mm (1/4") M8 x 1.25 mm (5/16") M10 x 1.5 mm (3/18") M12 x 1.75 mm (15/32") M14 x 2 mm (9/16") M16 x 2 mm (5/8")
Effective sectional area
of thread (mm2)14.2 20.1 36.6 58.0 84.3 115 157
•Thread diameter and appropriate tightening torque
Fig. 4

-16-
7-3-3. Bolt tightening torque characteristics
Figures 5-1 and 5-2 show relationships between time and tightening torque for individual bolt
types and sizes. While the data are useful for handy reference, actual tightening torque will vary
depending on tightening conditions and other variables. For details, please refer to Para. 8-3
"Tightening Torque Variation."
NOTE:
• The term "tightening time" indicates the impact time after the lower surface of the bolt
has come in contact with the material into which it is being tightened.
• In the tightening conditions shown in Figs. 5-1 and 5-2, the screws are being tightened
directly into a steel plate; accordingly, the torque goes up very abruptly in comparison
with ordinary bolt tightening conditions.
*Thefollowingboltswereutilized: Strengthgradeisreadasfollows:
Ordinary bolt; Strength grade 4.8 4.8
High-strength bolt; Strength grade Yield point or durable force:
12.9 320 N/mm2(32 kgf/mm2, 45,500 psi)
Tensile strength of the bolt:
400 N/mm2(40 kgf/mm2, 56,900 psi)
•Model WH 14DSL
Tightening in the save mode Tightening in the power mode
Fig. 5-1
Steel plate thickness: t

-17-
•Model WR 14DSL
Tightening in the save mode Tightening in the power mode
Fig. 5-2