1

Part I Conceptual Analysis of a Power Drill

2

1. Details and opinions regarding the DeWalt DC728KA Power Drill

The DC728KA drill also features a dual speed range from 0-400/ 0-1,400 rpm; and a high performance frameless motor which provides power of 270 unit watts. The DeWalt DC728KA also includes additional features such as an LED work light to increase visibility, a 1/2" ratcheting chuck which reduces slippage, a one hour battery charger with 2 (14.4v) batteries, and a convenient carry box.

Features

Compact and lightweight drill size; 4.7 pounds Dual speed range from 0-400/ 0-1,400 rpm High performance frame-less motor; 270 unit watts 1/2" ratcheting chuck to reduce slippage LED work light One hour battery charger; 2 (14.4v) batteries Convenient carry box Screwdriver bit

3

Specs

Voltage: 14.4v Max Power: 270 UWO Speed Settings: 2 Max RPM: 1400 Clutch Settings: 17 Chuck Size: 1/2" Chuck Type: Plastic, single sleeve Weight: 4.7 pounds

The Pros - Batteries generally run a long time between charges. Comfortable ergonomics around the handle, easy to hang on to. Enough power to work through materials quickly. The Cons - Batteries tend to wear out over the course of a year and not hold a charge. Replacement batteries are expensive for Dewalt tools.

The DeWalt DC728KA is a mid-grade "heavy duty" electric drill designed for users that require a drill that can fit into tight spaces. The DC728KA features a 4.7 pound lightweight design that DeWalt claims will "help minimize user fatigue".

Fig. 1.1 Exploded view of the Power Drill 3D model, showing interior components

4

2. The concept of the power drill and its components

1. DC Motor. 2. 1st step planetary set with 3 satellites. 3. 2nd step planetary set with 3 satellites. 4. Transmission shaft. 5. Drill bit. 6. Wall (or any undrilled material of compatible nature). 7. On/Off Switch. 8. Battery (Energy Source).

Fig. 2.1 Conceptual drawing of the power drill

5

3. The overall function of the power drill, the flows and the sub-functions of the overall function.

3.1 The overall function of the power drill (fig. 2.1) The Power Drill creates a hole by mechanically displacing a volume of material from a given solid material. It does so by using electric energy and a human drive-control system.

Input entities:

- Of material type: the drilling device itself; the undrilled material. - Of energetic type: muscular energy; electric energy. - Of informational type: data regarding the type of material that needs to be drilled

and the desired depth of hole; data and instructions regarding the operation of the drilling device; the starting signal.

Output entities:

- Of material type: drilled material; displaced material. - Of energetic type: heat and noise; heat, chemical energy. - Of informational type: the final depth of the whole.

Global function

M

E

I

M*

E*

I*

M

E

I

M*

E*

I*

FM

FE

FI

Fig. 3.1 Global function

Fig. 3.2 Function structure

6

3.2 The function structure of the power drill (fig 2.2) The FM sub-function: Reduction of the volume of the undrilled material. Input: undrilled material, mechanical energy; Output: drilled material, displaced material.

The FE sub-function: transformation of electrical energy into mechanical energy. Input electrical energy and connection/disconnection signals. Output mechanical energy accompanied by heat and noise.

The FI sub-function: Conversion of the input data (readiness of the device, current hole depth, desired hole depth, undrilled material nature) into stop/start signals and output data (final depth of the hole).

For the global function of the Power Drill, the material flow is the main flow while energetic and informational flows are secondary. Therefore, FM is the main sub-function and FE, FI are secondary sub-functions.

4. Symbolic representation of the function structure of the power drill.

FE2

M FM1 FM3 FM4 FM5 M1

*

M2*

E FE1 FE3 FE5 E* FE6

I

FI1 FI3 FI4

FI2

I*

FE4

Undrilled material

Drilled material

Displaced material Electrical energy

Heat and noise emission

Human control system

Final depth of the hole.

E FE2 FE

M FM

FM2

FM2

Power drill

Muscular energy

7

5. Statement of each component sub-function of the power drill and identification of the afferent partial solution from the principle solution.

FE1 Transformation of muscular energy into mechanical energy.

FE2 Modification of several state parameters of the mechanical energy. The human arm behaves like a mechanism.

FM1 Connecting the drilling device to the mechanical energy provided by the human arm (energy from the E flux).

FM2 Bringing the drilling device into the desired position for commencing the actual drill.

FM1 Connecting the undrilled material to the drilling device. The drilling device itself serves as material in the M flux, and is now connected to the main material flow.

FM2 Connecting the undrilled material to the mechanical energy. The contact between the undrilled material and the actual drill bit, which performs a rotational movement.

FM3 Reducing the materials volume. The hole is produced with the aid of the drill bit, which by rotating removes a part of the material.

FM4 Recording the holes depth. This is accomplished by retracting the device and visually inspecting the so far achieved result.

FM5 Separating the drilled material, obtained as a result, and the displaced material.

FE1 Connecting/disconnecting the electric power from the electrical source to the On/Off command. The battery from the handle of the drilling device is connected to the switch placed higher on the devices handle.

FE2 Transformation of electrical energy into rotational mechanical energy of the electrical DC motor, employing the effect of electromagnetic force.

FE3 Modification of the rotational speed of the mechanical energy provided by the motor, by reducing its rotations per minute with the aid of a planetary set, and thus increasing the torque.

FE4 Further reducing the rotational speed and, respectively, further increasing the torque with the aid of a second planetary set.

FE5 Transmission of the rotational mechanical energy from the last planetary set to the drill bit through the aid of a rotational shaft.

FE6 Emission of heat and noise, caused by friction between the components.

8

FI1 Emission of the start signal and transmission of the information regarding the depth of the hole.

FI2 Command of the execution signals for starting and stopping the device.

FI3 Reception of the information regarding the desired depth of the hole, and the current depth of the hole.

FI4 Emission of the stopping signal when the two depths described above become equal and the recording of the final depth of the hole.

6. Explanation of the solving principle of three sub-function (effect + effect carriers + configuration)

The three chosen sub-functions and their solving principles will be: FE2, FE3 and FM3.

FE2 - Transformation of electrical energy into rotational mechanical energy.

Physical effect The effect of electro-magnetic force.

Effect carrier The electric DC motor.

Configuration

- Power P = 270 W. - Voltage Range U = 14.4V - Rotational Speed n = 9800 rpm. - Torque T = 0.75 N*m. - Diameter d = 28 mm.

FE3 Reduction of the rotational speed and increase of the torque.

Physical effect The Hooke effect.

Effect carrier The first planetary set.

Configuration

- Transmission ratio i = 8. - Number of teeth Z1=7, Z3=58. - Diameters d1 = 7 mm d2 = 10 mm d3 = 28mm.

FM3 - Reducing the materials volume.

9

Physical effect shearing effect.

Effect carrier the attachable drill bit.

Configuration

- Nominal diameter d1 = 3 to 15 mm. - Drill diameter - d2 = d1 = 3 to 15 mm. - Length l1 = 19 to 35 mm. - Flute length l2 = 3 to 18 mm

7. Explanation of the correlations between input and output signals of a logical sub-function

FM2 - Connecting the undrilled material to the mechanical energy.

X The undrilled material. Y Rotational mechanical energy. A The drilling of the material.

X = 0 The undrilled material does not exist.

X = 1 The undrilled material exists.

Y = 0 The drill bit does not rotate (there is no mechanical energy).

Y = 1 The drill bit rotates (there is mechanical energy).

A = 0 The undrilled material remains unaltered.

A = 1 The undrilled material suffers displacement (shearing).

X 0 0 1 1 Name

Y 0 1 0 1 A 0 0 0 1 AND

FM2

x

y A

10

Part II Conceptual Synthesis of a Power Drill

11

1. Requirements List (PDS) for a Power Drill

Type Requirements

- C - C - C - C - D

1.Performance - Target torque: Tm=25 N*m At least 22 times the motor torque. - Speed without load: n=0 850 rot/min. - Drill bit nominal diameter: d=3 to 10 mm. - Drilling depth in wood and metal: hw=30 mm, hm=10 mm. - With torque adjustment.

- C - C - C - D - D

2. Size - Length: l 230 mm. - Width: w 80 mm. - Height: h 230 mm. - Radial Overall Size of the housing

12

2. Global function and sub-function structure of the Power Drill

Overall function of the Power Drill (function responsible for speed decrease and torque increase).

Sub-function structure of the Power Drill.

3. Morphological Matrix

Sub-function Physical Effect Potential Principle Solutions

FE1 Connecting/Disconnecting from the electrical source (battery).

Conductive materials contact effect.

On/Off Switch. Round potentiometer

switch.

Switch with resort for

comeback.

FE2 Transforming electrical energy into mechanical energy

Electromagnetic force effect.

DC Motor. Stepper Motor.

FE3 Reducing the rotational speed (amp. torque) First stage. Lever effect. Worm drive

with fixed axes. Spur gear pair

with fixed axes. Planetary

Gear.

FE4 Transmitting mechanical energy to the drilling object.

Coulombian friction effect

Spinning shaft with threaded

hole.

Spinning shaft With hexagonal

hole.

Spinning shaft attached to

chuck..

FE5 Minimizing losses through friction

Coulombian friction effect.

Superior quality fabrication.

Forced lubrication.

The morphological matrix is used to combine several potential principal solutions into

more solving variants of the overall function, as in the following table.

Subfunction

Solving Variant

FE1 FE2 FE3 FE4 FE5

SV1 1.1 2.1 3.1 4.1 5.1 SV2 1.2 2.2 3.2 4.2 5.1

SV3 1.3 2.1 3.3 4.3 5.2+5.1

SV4 1.3 2.1 3.3+3.3 4.3 5.2+5.1

SV5 1.3 2.2 3.3 4.3 5.1

1.1 1.2 1.3

2.1 2.2

3.1 3.2 3.3

4.1 4.2 4.3

5.1 5.2

FE

FE2 E FE1 FE3 FE4 FE5

Electrical energy

Lost energy

Useful energy

Electrical energy

Lost energy

Useful energy

13

4. Establishment of conceptual variants based on the requirements (Predimensioning)

Case of variant SV1 Worm drive with fixed axes (1.1+2.1+3.1+4.1+5.1).

i = i1,2h = i1,2 = 12 = + Z2Z1 = 25 We adopt Z1 = 1 because of radial overall size => Z2 = 25

Presuming that the angle of fall for the worm 1 is smaller than the angle of friction (1

14

Case of variant SV2 Spur gear with fixed axes in three stages (1.2+2.2+3.2+4.2+5.1)

i = i1,6 = i1,2 i3,4 i5,6 = 16 = (Z2Z4Z6)(Z1Z3Z5) = 25 i1,2 i3,4 i5,6 = 36i1,2 = i3,4 = i5,6 => i1,2 = i3,4 = i5,6 = 253 = 2.92

It is impossible to have the same ratio at all stages, therefore we will try:

i1,2 = 4i1,2 i3,4 i5,6 = 25i1,2 = i3,4 = i5,6 => i3,4 = i5,6 = 254 = 6.25 = 2.5

1 = 83 = 105 = 10 => 2 = 284 = 256 = 25

Direct efficiency:

= 1,6 = (0.98)3 = . Inverse efficiency:

inv = 6,1 = . Conclusion The three stage spur gear reducer also manages to accomplish and exceed the minimum torque increase, however it does not fulfill the auto-blocking condition and therefore a brake is needed.

15

Case of variant SV3 Planetary gear with one stage (1.3+2.1+3.3+4.3+(5.1+5.2))

i = i1,H3 = 1,3H,3 = 1,H 3,HH,H 3,H = 1,H3,H + 10 + 1 = 1 1,H3,H = 1 i0 => => 1 i0 = 25 => i0 = 24

, i0 = i1,3H = 1,H3,H = i1,2H i2,3H = 21 32 => i0 = 31 => => 31 = 24 => Z1 = 8 and therefore Z3 = 200 Because aw1 = aw2 => rw1 + rw2 = rw3 rw2 = Z1 + Z2 = Z3 Z2 => => 8 + Z2 = 200 Z2 => 8 + 2Z2 200 = 0 => Z2 = 200 82 = 96

Direct efficiency:

= 1,H3 = THH,3T11,3 = THT11,3H,3 =

THT1i1,H3 = 1 i0 011 i0 = 1 + 25 0.9711 + 25 = . !1.0291 !

, 0 = 1,2H 2,3H = (0.985)2 = 0.97

16

Inverse efficiency:

inv = H,13 = T11,3THH,3 = T1THH,31,3 =

T1THiH,13 = 1 i01 i0 01 = 1 + 351 + 35 0.971 = 1.0291 !. !

Conclusion - The single planetary unit reducer also made it into the conceptual variant stage by fulfilling the required torque increase and reduction ratio. It also needs a brake to prevent reversible transmission.

Case of variant SV4 Planetary gear with two stages (1.3+2.1+(3.3+3.3)+4.3+(5.1+5.2))

i = i1,H2 = i1,H13 i4,H26 = 1,3H1,3 4,6H2,6 = 1,H1 3,H1H1,H1 3,H1 4,H2 6,H2H2,H2 6,H2 = 1,H13,H1 + 10 + 1 4,H36,H2 + 10 + 1 = 1 1,H13,H1 1 6,H26,H2 = (1 i01) (1 i02) = +25

i01 = i02 => 1 i01 = 25 => i01 = i02 = 4 , 01 = i1,3H1 = 1,H13,H1 = i1,2H1 i2,3H1 = Z2Z1 Z3Z2 => 01 = Z3Z1

17

02 = i4,6H2 = 4,H26,H2 = i4,5H2 i5,5H2 = Z5Z4 Z6Z5 => 02 = Z6Z4

Z6Z4 = Z3Z1 = 4 Z1 = 8 => Z3 = 32Z4 = 8 => Z6 = 32 Because aw1 = aw2 => rw1 + rw2 = rw3 rw2 = Z1 + Z2 = Z3 Z2 => => 8 + Z2 = 32 Z2 => 8 + 2Z2 32 = 0 => Z2 = 32 82 = 16, Z5 = 32 82 = 16

Direct efficiency:

01 = 1,3H1 = (0.985)2 = 0.97 02 = 4,6H2 = (0.985)2 = 0.97

1,3H1 = TH1H1,3T11,3 = TH1T11,3H1,3 =

TH1T1i1,H13 = 1 i01 0111 i01 = 1 + 4 0.9711 + 4 = . !1.0251 !

4,6H2 = TH2H2,6T44,6 = TH2T44,6H2,6 =

TH2T4i4,H26 = 1 i02 02 11 i02 = 1 + 5 0.9711 + 5 = . !1.0251 !

= 1,H2 = 1,3H1 4,6H2 = (0.9750)2 = . Inverse efficiency:

H2,46 = T44,6TH2H2,6 = T4TH2H2,64,6 =

T4TH2iH2,46 = 1 i021 i02 021 = 1 + 41 + 4 0.971 = 1.0251 !. !

H1,13 = T11,3TH1H1,3 = T1TH1H1,31,3 =

T1TH1iH1,13 = 1 i011 i01 011 = 1 + 51 + 5 0.971 = 1.0251 !. !

inv = H2,1 = H2,46 H1,13 = (0.9748)2 = .

18

Conclusion The two unit planetary reducer accomplishes and exceeds the imposed minimum torque and ratio. It does so with a lower efficiency, but drastically improving radial overall size in comparison to its single unit cousin. Because inv>0 the autoblocking condition is not accomplished and it also needs a brake.

Case of variant SV5 Planetary reducer with a sun gear - composed of pin coupling and cycloidal gear pair with rollers (1.3+2.2+3.3+4.3+5.1)

i = iH,13 = H,41,3 = H,H 3,H1,H 3,H = 0 + 11,H3,H + 1 = 11 i1,3H = 11 i0 = 25 => => i0 = 1.04

, i0 = i1,3H = 1,H3,H = i1,2H i2,3H = (+1) + Z3Z2 = 32 => 32 = 1.04 => 2 = 25 => 3 = 25 1.04 = 26

Direct efficiency:

0 = 1,3H = 1,3H 1,3H = (0.999)2 = 0.998 = H,13 = T11,3THH,3 = T1THH,3

1,3 =

T1THiH,13 = 1 i01 i0 01 = 1 1.041 1.04 0.9981 = 1.0548 !. !

19

Inverse efficiency:

inv = 1,H3 = THH,3T11,3 = THT11,3H,3 =

THT1i1,H3 = 1 i0 011 i0 = 1 1.03 0.99811 1.03 = . !1.0520 !

Conclusion this reducer achieves the imposed torque with slightly lower efficiency but with improved overall size.

5.1 Rough evaluation of the conceptual variants

Solving Variant CV1 CV2 CV3 CV4 CV5 TECHNICAL CHARACTERISTICS

1. Numbers of teeth Z1=1 Z2=25

Z1=8 Z2=28 Z3=10 Z4=25 Z5=10 Z6=25

Z1=8 Z3=200

Z1=8 Z3=32 Z4=8

Z6=32

Z2=25 Z3=26

2.The reduction ratio for the input speed 25 -25 25 25 -25

3. The efficiency of a gear pair with fixed axes 0.65 0.98 0.985 0.985 0.999

4. The efficiency of the reducer 12=0.65 16=0.941 1H=0.9711 1H2=0.952 H1=0.9504

5. Efficiency in case of reverse actuation 21=0.65 61=0.941 H1=0.9711 H2,1=0.9521 1H=0.9480

6. Amplification ratio of the input torque 16.25 23.52 24.27 23.80 23.76

EVALUATION CRITERIA/ Grades A. Minimizing losses through friction. 6 8 9 9 8

B. Reducing overall radial size. 7 7 3 7 9

C. Reducing overall axial size. 9 6 8 6 9

D. Minimizing production costs 8 5 8 6 8

E. Minimizing degree of complexity. 8 6 8 7 9

F. Minimizing weight for operation 7 6 5 8 9

= 45 38 41 43 50 R=/(6x10)= 0.75 0.63 0.68 0.72 0.86

Place 2 5 4 3 1

20

The technical characteristics of the valid solving variants from the upper part of the chart can be correlated to one or more of the evaluation criteria. Depending on the value of the technical characteristic each conceptual variant receives a mark from 1 to 10. Finally an average is made and all variants are ordered. Evaluation criterions are of equal importance.

5.2 Fine evaluation of the conceptual variants

k Criteria

Criteria A B C D E F Pk Lk Sk Wk wk

1 A 0.5 1 1 1 1 1 5.5 1 5 5.33 0.42 2 B 0 0.5 1 1 1 1 4.5 2 4 3.25 0.26 3 C 0 0 0.5 1 1 1 3.5 3 3 2.00 0.16 4 D 0 0 0 0.5 1 1 2.5 4 2 1.17 0.09 5 E 0 0 0 0 0.5 1 1.5 5 1 0.57 0.04 6 F 0 0 0 0 0 0.5 0.5 6 0 0.12 0.01

Sum: 12.44 1.00

FRISCO Formula: Wk = 2PkPmin +Smin +0.50.5nPmax Pk wk = wkwk

Wk = 2 5.5 0.5 + 5 + 0.50.5 6 5.5 5.5 = 5.33 wk = 5.3312.44 = 0.42 Wk = 2 4.5 0.5 + 4 + 0.50.5 6 5.5 4.5 = 3.25 wk = 3.2512.44 = 0.26 Wk = 2 3.5 0.5 + 3 + 0.50.5 6 5.5 3.5 = 2.00 wk = 212.44 = 0.16 Wk = 2 2.5 0.5 + 2 + 0.50.5 6 5.5 2.5 = 1.17 wk = 1.1712.44 = 0.09 Wk = 2 1.5 0.5 + 1 + 0.50.5 6 5.5 1.5 = 0.57 wk = 0.5712.44 = 0.04 Wk = 2 0.5 0.5 + 0 + 0.50.5 6 5.5 0.5 = 0.12 wk = 0.1212.44 = 0.01

In order for the evaluation to be more accurate and more flexible to the different importance of the evaluation criterions, we need to establish the relative weight coefficients for each of the criterion. This is done by using the FRISCO formula and a table which identifies if one criterion is more important than another.

21

For the evaluation to be complete, the first four places (in this case, still 5 solving variants) are subjected to fine evaluation by weighting the marks previously obtained at the rough evaluation stage.

6. The conceptual solution

As the fine evaluation indicates the conceptual variant which employs a planetary reducer with a central gear comprising of a pin coupling and a cycloid drive, is the most suitable solution for fulfilling the established requirements both quantitatively and qualitatively and for meeting the evaluation criterions with best marks in correspondence with their importance. The main advantages are:

- Amplification of the initial torque by 33.68 times efficiency increases when the gear ratio decreases.

- Improved axial and radial overall size. - Relatively simple fabrication technology, although it requires high precision.

CV1 CV2 CV3 CV4 CV5 Criteria wk Nk wk

.Nk Nk wk.Nk Nk wk

.Nk Nk wk.Nk Nk wk

.Nk A 0.42 6 2.52 8 3.36 9 3.78 9 3.78 8 3.36 B 0.26 7 1.82 7 1.82 3 0.78 7 1.82 9 2.34 C 0.16 9 1.44 6 0.96 8 1.28 6 0.96 9 1.44 D 0.09 8 0.72 5 0.45 8 0.72 6 0.54 8 0.72 E 0.04 8 0.32 6 0.24 8 0.32 7 0.28 9 0.36 F 0.01 7 0.07 6 0.06 5 0.05 8 0.08 9 0.09

Sum 45 6.89 38 6.89 41 6.93 43 7.46 50 8.31 Place 4 4 3 2 1

22

6.1 Quality Function Deployment Analysis

1.Ta

rget

Tor

que

2.Ro

tatio

nal S

peed

3.Dr

ill B

it Co

mpa

t.

4.To

rque

Adj

ustm

ent

5.Vo

lum

e W

xLxH

6.Dr

illin

g De

pth

7.Po

wer

8.W

eigh

t

9.Ba

tter

y Li

fe

10.R

echa

rge

Spee

d

11.O

pera

ting

Tem

p.

12.O

pera

ting

Hum

.

13.O

pera

ting

Alt.

14.C

ompa

tible

Par

ts

15.A

ttac

habl

e Ha

ndle

16.L

ife S

pan

17.W

arra

nty

18.M

ater

ial

1.Powerfull 9/ 0.9

3/ 0.3

1/ 0.1

1/ 0.1

2.Fast

9/ 0.72

1/ 0.08

1/ 0.08

1/ 0.08

3.Adjustable

3/ 0.24

9/ 0.72

4.Easy to handle

3/ 0.3

3/ 0.3

1/ 0.1

3/ 0.3

9/ 0.9

1/ 0.1

5.Easy to transport

9/ 0.63

3/ 0.21

1/ 0.07

6.Stability 1/ 0.07

3/ 0.21

1/ 0.07

1/ 0.07

3/ 0.21

7.Autonomic

3/ 0.24

9/ 0.72

3/ 0.24

8.Compliant STD

9/ 0.72

1/ 0.08

9/ 0.72

9.Cheap 3/ 0.3

1/ 0.1

3/ 0.3

3/ 0.3

9/ 0.9

10.Later support

3/ 0.21

1/ 0.07

9/ 0.63

11.Durability

1/ 0.1

1/ 0.1

3/ 0.3

1/ 0.1

9/ 0.9

12.Working Cond.

3/ 0.21

3/ 0.21

3/ 0.21

1/ 0.07

Absolute Importance 1 1.12 1.04 1.23 0.93 0.31 0.89 0.51 0.90 0.32 0.31 0.51 0.17 1.23 0.97 0.07 0.63 2.18 14.32 Relative Importance 0.07 0.08 0.07 0.09 0.06 0.02 0.06 0.04 0.06 0.02 0.02 0.04 0.01 0.9 0.07 0.01 0.04 0.15 1 Competing Product 35 750 Z N 45 30 230 2.5 2 2 40 60 3500 Y N 5 1 Z

Own Product 38 600 X Y 42 35 250 2.2 2.5 2 45 70 3500 Y Y 5 1 X Target Values 40 800 x y 40 35 250 2 3 - 50 80 3500 Y Y 5 2 X Measure Units N*m rpm - y/n cm3 mm W kg h h C % m y/n y/n yrs yrs tip

9

9 1

1 3

3 3

3

3

3

1 1

1

1

3

3

3 3

3

23

The Quality Function Deployment (QFD) analysis has the goal of identifying means to improve a Power Drill which is already functional and on the market. The table above correlates technical characteristics with the requirements of the customer and determines weight coefficients to both, indicating where the improvement is most needed.

The

requ

irem

ents

As

sess

men

t of

the

com

petin

g

Asse

ssm

ent o

f th

e ow

n Ta

rget

Val

ues

for

Ra

te o

f im

prov

emen

t

Abso

lute

W

eigh

t Re

lativ

e W

eigh

t

1.Powerfull 5 4 5 5 1 5 0.10

2.Fast 4 4 4 4 1 4 0.08

3.Adjustable 3 3 3 4 1.33 3.99 0.08

4.Easy to handle 4 2 4 5 1.25 5 0.10

5.Easy to transport 3 4 4 4 1 3 0.07

6.Low vibrations 2 2 3 4 1.33 2.67 0.07

7.Autonomic 3 4 3 4 1.33 3.99 0.08

8.Compliant STD 4 3 4 4 1 4 0.08

9.Cheap 5 4 5 5 1 5 0.10

10.Later support 3 4 4 4 1 3 0.07

11.Durability 4 3 4 5 1.25 5 0.10

12.Working Cond. 2 2 2 3 1.5 3 0.07

47.65 1

FeaturesSpecs