Mechanical Design

Mechanical Design

Abstract

:

A machine is a combination of mechanisms and other components which transforms, transmits, or utilizes

energy, force, or motion for a useful purpose. Examples are engines, turbines, vehicles, hoists, printing presses,

washing machines, and movie cameras. Many of the principles and methods of design that apply to machines also

apply to manufactured articles that are not true machines, from hub caps and filing cabinets to instruments and

nuclear

pressure

vessels.

The

term

design

is

used

in

a

broader

sense

than

design

to

include their design. For some apparatus, the thermal and fluid aspects that determine the requirements of heat,

flow path, and volume are separately considered. However, the motion and structural aspects and the

provisions for retention and enclosure are considerations in mechanical design. Applications occur in the field

of mechanical engineering, and in other engineering fields as well, all of which require mechanical devices, such as

switches, cams, valves, vessels, and mixers.

Keywords

: Mechanical Designmechanisms Design Process Tolerance

An overview of mechanical design

The first step in the manufacture of any product is design. Mechanical design is the application of science and

technology to devise new or improved products for the purpose of satisfying human needs. It is a vast field of

engineering technology which not only concerns itself with the original conception of the product in terms of its

size,

shape

and

construction

details,

but

also

considers

the

various

factors

involved

in

the

manufacture

，

marketing and use of

the product.

People

who

perform

the

various

functions

of

machine

design

are

typically

called

designers,

or

design

engineers.

Mechanical

design

is

a

creative

activity. However,

in

addition

to

being

innovative,

a

design

engineer

must

also

have

a

solid

background

in

the

areas

of

mechanical

drawing,

kinematics,

dynamics,

materials

engineering, strength of materials and manufacturing processes.

Here

we

take

the

selection

of

materials

as

an

example.

During

recent

years

the

selection

of

engineering

materials

has

assumed

great

importance.

Moreover,

the

process

should

be

one

of

continual

reevaluation.

New

materials

often

become

available

and

there

may

be

a

decreasing

availability

of

others.

Concerns

regarding

environment

pollution,

recycling

and

worker

health

and

safety

often

impose

new

constraints.

The

desire

for

weight

reduction

or

energy

savings

may

dictate

the

use

of

different

materials.

Pressures

from

domestic

and

international

competition,

increased

serviceability

requirements,

and

customer

feedback

may

all

promote

materials reevaluation. The extent of product liability actions, often the result of improper material use, has had a

marked

impact.

In

addition,

the

interdependence

between

material

and

their

processing

has

become

better

recognized.

The

development

of

new

processes

often

forces

reevaluation

of

the

material

being

processed.

Therefore,

it

is

imperative

that

design

and

manufacturing

engineers

exercise

considerable

care

in

selecting,

specifying,

and

utilizing

materials

if

they

are

to

achieve

satisfactory

results

at

reasonable

cost

and

still

assure

quality.

In mechanics processing

，

milling and grinding are always under the consideration of the designers. With the

exceptions of turning and drilling, milling is undoubtedly the most widely used method of removing metal. Well

suited and readily adapted to the economical production of any quantity of parts, the almost unlimited versatility

of

the

milling

process

merits

the

attention

and

consideration

of

designers

seriously

concerned

with

the

manufacture of their product.

Grinding is one of the most widely used methods of finishing parts to extremely close tolerances and low

surface

roughness.

Currently,

there

are

grinders

for

almost

every

type

of

grinding

operation.

Particular

design

features of a part dictate to a large degree the type of grinding machine required. Where processing costs are

excessive, parts redesigned to utilize a less expensive, higher output grinding method may be well worthwhile. For

example,

wherever

possible

the

production

economy

of

center

less

grinding

should

be

taken

advantage

of

by

proper design consideration.

Although grinding is usually considered a finishing operation, it is often employed as a complete machining

process on work which can be ground down form rough condition without being turned or otherwise machined.

Thus

many

types

of

forgings

and

other

parts

are

finished

completely

with

the

grinding

wheel

at

appreciable

savings of time and expense.

Besides,

the

application

of

nontraditional

manufacturing

processes

will

bring

more

bold

and

innovative

design.

The

conventional

manufacturing

processes

in

use

today

for

material

removal

primarily

rely

on

electric

motors

and

hard

tool

materials

to

perform

tasks

such

as

sawing,

drilling,

and

broaching.

Conventional

forming

operations are performed with the energy from electric motors, hydraulics, and gravity. Likewise, material joining

is conventionally accomplished with thermal energy sources such as burning gases and electric arcs.

In

contrast,

nontraditional

manufacturing

processes

harness

energy

sources

considered

unconventional

by

yesterday’s standards. Material removal can now be accomplished with electrochemical reactions, high

-velocity

jets of liquids and abrasives. Materials that in the past have been extremely difficult to form, are now formed with

magnetic fields, explosives, and the shock waves from powerful electric sparks.. Material-joining capabilities have

been expanded with the use of high-frequency sound waves and beams of electrons.

In

the

past

50

years,

over

20

different

nontraditional

manufacturing

processes

have

been

invented

and

successfully implemented into production. The reason there are such a large number of nontraditional processes

is

the

same

reason

there

are

such

a

large

number

of

conventional

processes

;

each

process

has

its

own

characteristic attributes and limitations, hence no one process is best for all manufacturing situations.

In

other

cases,

nontraditional

processes

are

used

to

reduce

the

number

of rejects

experienced

by

the

old

manufacturing

method

by

increasing

repeatability,

reducing

in-process

breakage

of

fragile

work

pieces,

or

by

minimizing detrimental effects on work piece properties.

As stated previously, the purpose of mechanical design is to produce a product which will serve a need for

man. Inventions, discovery and scientific knowledge by themselves do not necessarily benefit people; only if they

are

incorporated

into

a

designed

product

will

a

benefit

be

derived.

It

should

be

recognized,

therefore,

that

a

human need must be identified before a particular product is designed.

Mechanical design should be considered to be an opportunity to use innovative talents to envision a design

of a product, to analyze the system and then make sound judgments on how the product is to be manufactured. It

is

important

to

understand

the

fundamentals

of

engineering

rather

than

memorize

mere

facts

and

equations.

There are no facts or equations which alone can be used to provide all the correct decisions required to produce a

good design. On the other hand, any calculations made must be done with the utmost care and precision.

Good design require trying new ideas and being willing to take a certain amount of risk, knowing that if the

new idea not work the existing method can be reinstated. Thus a designer must have patience, since there is no

assurance of success for the time and effort expended. Creating a completely new design generally requires that

many old and well-established methods be thrust aside. This is not easy since many people cling to familiar ideas,

techniques and attitudes. A design engineer should constantly search for ways to improve an existing product and

must decide what old, proven concepts should be used and what new, untried ideas should be incorporated.

During

the

beginning

stages

of

design,

creativity

should

be

allowed

to

flourish without

a

great

number

of

constraints. Even though many impractical ideas may arise, it is usually easy to eliminate them in the early stages

of design before firm details are required by manufacturing. In this way, innovative ideas are not inhibited. Quite

often, more than one design is developed, up to the point where they can be compared against each other. It is

entirely possible that the design which is ultimately accepted will use ideas existing in one of the rejected designs

that did not show as much overall promise.

Another important point which should be recognized is that a design engineer must be able to communicate

ideas to other people if they are to be incorporated. Initially, the designer must communicate a preliminary design

to get management approval. This is usually done by verbal discussions in conjunction with drawing layouts and

written

material.

To

communicate

effectively,

the

following

questions

must

be

answered

:(1)

Does

the

design

really serve a human need?(2) Will it be competitive with existing products of rival companies?(3) Is it economical

to produce?(4) Can it be readily maintained?(5)Will it sell and make a profit?

Design Process

The design begins from real of or the demand of imagination. The existing instrument may need to take in to

improve

on

the

enduring,

efficiency,

weight,

speed

or

the

cost.

May

need

new

instrument

to

complete

before

function done by person, such as Assemble or maintain. The target is all or partly after making sure, design of the

next move is to conceive outline the organization that can complete the function needed and it arranges for this,

drawing grass diagram to be worth barehanded biggest, it isn't only one personal record of viewpoint with others

discussion

of

assistance

means,

and

be

suitable

for

to

communicate

with

own

viewpoint

particularly,

is

the

stimulant which creates sex way of thinking to still need extensive knowledge concerning parts, because a the set

new

machine

usually

from

be

familiar

with

of

each

kind

of

spare

parts

reschedule

or

substitute

but

become,

changed size and material perhaps. Regardless at conceive outline process in still after, a design will carry on a fast

or rough calculation or analyze to make sure regulation size and possibility. When some concerning need or can

use amount of space of viewpoint assurance after, can start pro rata painting grass diagram.

Finally, I completed according to the design of the function and the credibility, can make kind machine. If test

satisfied, and if the device wants mass production, will to the first design carry on a certain modification to insure

with

lower

cost

mass-produce.

Later

on

several

years

of

make

and

use

a

period,

design

probably

because

of

conceive

outline

new

viewpoint

perhaps

according

to

test

and

experience

foundation

of

further

analytical

the

change shown but change. Sell attraction, customer's satisfaction and manufacturing costs to all have something

to do with design, the success which designs ability and engineering investment is closely related.

Some design standards

At this part, someone suggests the attitude of the usage creation carries on of analysis, this kind of analysis

can

cause

a

graveness

improvement

and

to

back

up

the

product

conceive

outline

with

perfect,

perhaps

the

product

function

is

more,

more

economic

and

more

enduring.

Creating

the

stage's

needing

not

is

first

with

independent stage. Although analyze personnel the whole probably

irresponsible design, he isn't only the right

answer of[with] problem that can be from the numeral put forward wanting him to resolve only, not only is give

should dint value, the size works to limit perhaps. He can put forward more extensive views, for the purpose of

improvement norm or project. Because in the analysis the front or the analysis the process, he will acquaint with

to

equip

and

its

work

condition,

he

is

fully

placed

in

a beneficial

position

which

conceives

outline

to

choose a

project.

Best

he

can

put

forward

a

suggestion

change

shape

to

Elimination

moment

of

force

or

should

dint

concentration, not allow to set up to have to cut the organization that noodles and excessive dynamic state carry a

lotus greatly best is he discards his meticulous of design but is not see a machine discard afterwards.

For

stiring

up

to

create

sex

thinking,

the

suggestion

designs

a

personnel

and

analytical

the

personnel

use

following standard.6 ex- standards are particularly applicable to an analysis personnel, although he may involve to

all this 10.

1. Create the physical function that sex land utilization need when using combine the control don't need.

2. Know practical carry lotus and its importance.

3. Consider in advance there is no function carrying a lotus.

4. Invent to add to carry a condition more beneficially.

5. Provide minimum weight the most beneficial of distribute in response to the dint with rigid.