SMLease Design

Mechanical Product Design & Development Partner


Mechanical Design Guide is a collection of best articles for the mechanical design engineers uncovering collective knowledge about Sheet-Metal, Plastic, Casting Mechanical Product Design, Mechanical Tolerance, Tolerance Stackup, Plating, Final Finish Operations, Product Thermal Design 

In the guide you’ll find articles covering Complete Product Design and Development life cycle. You can contact us to start a new topic.

Sheet Metal Gauge Chart

In Sheet Metal manufacturing industry, the thickness of sheet metal sheet is commonly specified by a traditional, non-linear measure known as Gauges. Gauges are defined as per standard rolling mill available. Larger the value of gauge number smaller will be the sheet thickness. 

Sheet Metal Thickness Gauge Chart

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Heat Sink Selection Process

With increase in heat dissipation rate and reduction in overall form factor, thermal management of electronics devices is becoming very important part of electronics product design.

Electronics chip/IC/processor  performance, reliability and life are inversely proportional to the its temperature (higher the temperature lower will be the product life). By performing product thermal analysis in initial stage of product design you can save cost and product design life-cycle time can be reduced…

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General Tolerance : ISO-2768

Variations on dimensions without tolerances values are according to ISO 2768 for linear and angular dimensions. ISO 2768 is used to define the general tolerance on sheet-metal and plastic parts. For sheet-metal parts ISO 2768-m and for plastic parts ISO 2768-f is used as general tolerances 

This part of ISO 2768 is intended to simplify drawing indications and it specifies general tolerances for linear and angular dimensions without individual tolerance indications in four tolerance classes.

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Why 2nd angle and 4th Angle Projection is not Used

To understand why 2nd and 4th angle projection is not used? First we need to understand the concept of orthographic projection system.

Theoretically there are four projection system, out of which only 1st and 3rd angle projection system are used because of limitation of 2nd and 4th angle projection system.



How Projection System Works

To understand how projection system works We can consider a point in 1st and 3rd

quadrant (ref. image on right)

Consider Point …

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First Angle And Third Angle Projection

Orthographic Projection

Orthographic projection is a method of projection to draw engineering 2D drawings for an object using parallel lines to project different views on to a 2D plane.

Object can be placed in any of four quadrant. First angle and third angle projections are commonly used for making engineering drawing because of the limitation of 2nd and 4th angle projection.


First Angle Projection  


  • In the 1st angle pr…

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Modes Of Heat Transfer


Heat Transfer takes place from hot body to cold body. There are basically three modes of heat transfer by which heat can be transferred from hot body to cold body: Conduction, Convection & radiation. Any type of heat transfer from one body to another occurs by the combination of these three heat transfer modes. Heat transfer is one of very important aspect of product design.





Conductive heat Transfer

Conduction heat transfer is the transfer of heat betwe…

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Plastic Prototyping

Prototyping is very important stage in product design life cycle. Prototyping is done for initial validation and verification of design. Any modification in Injection mould requires money and time. Prototyping of plastic part is done to validate product design before injection moulding to reduce product timeline and cost.

Depending on product aesthetics & functional requirements, prototyping process is selected.

Plastic Prototyping Manufacturing Process


3D Printing

3D print…

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Technical Interview Questions for Fresher Mechanical Engineers : Part 2

Depending on the requirements and scope of work interviewer ask interview questions. Interviewer may ask you about your summer / industrial training, final year project and your favourite subject. 

Below we will discuss about some of commonly asked manufacturing interview questions from Fresher mechanical engineers:

What are the manufacturing operations that can be done with drilling machine?

Drilling, Reaming, Tapping, boring, counter-boring, countersinking and spot facing are som…

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Drilling Machine Manufacturing Operations

Drilling machine is commonly used for doing various manufacturing operations. Apart from drilling, other manufacturing operations can be done with drilling machine. For doing different manufacturing operations, Required drill bit is selected and machine speed is controlled. 



Drilling is metal cutting operation by rotating and pressing multi point cutting tool (called drill bit), to cut a circular hole in solid materials. Standard tool bits in different size are …

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Difference Between Soldering, Brazing and Welding

Soldering, brazing, and welding operations are used for joining two or more pieces of metal. All of these operations are different in terms of base material to be joined, joining temperature and filler material used.



Welding is a joining operation used to join two or more similar material (usually metal or thermoplastic parts) by melting base material or by using filler material rod. Strength of welded parts is similar to the base material. Sometimes pressure is also used a…

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Sheet Metal Electronics Enclosure Design

Sheet Metal electronics enclosure designs that reflect your design intent while satisfying product functional requirements and cost is a challenging task. This article will highlight key design consideration and their impact on product performance: material, assembly techniques, finish etc.


Product Industrial and Assembly Architecture Design


Table Top indoor Electronics EnclosureWall Mounting Enclosure19 Inch 1 U Electronics …

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DFMEA : Design Failure Mode & Effect Analysis

What is DFMEA

DFMEA (Design Failure Mode & Effect Analysis) is a part of FMEA (Failure Mode & Effect Analysis) used for identifying potential risks involved in a new design of a product or service. During DFMEA product design functions, failure modes, cause of failure and their effects with corresponding severity ranking, occurrence and detection is identified. 

DFMEA helps in identification of the effects of failures, actions that could eliminate or reduce the chances of the failures a…

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Role of Mechanical Design Engineer in PCB Design

Now a days all market disrupting big ideas are coming new startups and innovators who has no previous experience in product design. In initial design stage sometime innovators and startups gives more preference  to pcb hardware design without considering industrial and mechanical design of the product.

Hiring a Mechanical Design Service at the initial design stage of your pcb layout, can save redesign cost and reduce product time to market.

How Mechanical / Industrial Design can Affec…

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Difference Between Product Design and Product Development

Product Development

Product Development is a complete product development cycle from market analysis, product specifications, concept/industrial design, costing, scheduling, testing, manufacturing, Logistics, customer feedback, improvements and all other aspects of getting a product into the market.

Complete product development process includes involvement of marketing, design, purchase, manufacturing, sales and after sales support team.


Product Design

Product Design is co…

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Role Of Mechanical Design Engineer in Product Industrial / Aesthetics Design

Now a days all market disrupting big ideas are coming new startups and innovators who has no previous experience in product design. In initial design stage more preference are given to pcb design and industrial design of the product.

Hiring a Mechanical Design Service at the initial design stage can save lot of cost and reduce product time to market.


How Mechanical Design Affects Industrial Design Of a Product

  • Mechanical Product Design Services are required for a good produc…

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How a Good Mechanical Design Can Shorten The Timeline Of a product Development

Lot of challenges are faced in product manufacturing and pricing while launching a new product into market.

Launching a product into market is not a easy task. You need to do lot of market research, make concept, doing detailed design, product verification & validation and final tooling before going for production.

There are lot of instances when startups fails to launch a product despite having very good design & Market. Following are the some of the reasons product fails:

Timelines n…

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Ventilation Options For Sheet Metal Enclosures

Why Ventilation is Required ?

With reduction in size of electronics PCB and mechanical enclosure, Heat dissipation is becoming a challenge. To increase heat dissipation rate in sheet metal enclosures, ventilation holes are required. In sheet metal parts we can create ventilation holes that are aesthetically pleasing while satisfying the requirement of heat dissipation.

Heat transfer calculation for high heat dissipating components need to be done to find optimum area required for convec…

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Electronics Enclosure Design

Electronics enclosure designs that reflect your design intent, product requirements and cost is a challenging work . Few things like product aesthetics, market size, product life & cost need to be determined in the start of design 

This blog will highlight key design consideration and their impact on product performance: product aesthetics, material selection, assembly process, Budget and total number of parts need to be manufactured

If you have any questions, please comment below…

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How To Join Sheet Metal Parts

There are several options like screws, rivets, welding, adhessive, Clinching / tox round joint, folding, are some of commonly used sheet metal parts joining techniques. Selection of best process for joining sheet metal parts depends on the material, its thickness and application.

This guide will give you an overview of the techniques used to join / assembly sheet metal parts

You can contact us for mechanical design services and for any support related to sheet metal assembly proce…

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Types Of Washers & Their Application

Washer is a disk shaped thin plate with a centre hole used to distribute the load of a threaded fastener. Washers are also used as spacer, spring, for distributing load, pre-loading screws, to reduce vibration (rubber washer). Washers are made of metal, plastic, rubber or fiber.

Washers can be categorised in three types : Plain Washer, Spring Washer, Lock Washer

Plain Washer

Plain Washer are used to distribute load to prevent damage to the surface being assembled. Plain (Millar) …

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