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.

Basics of GD&T : SMLease Design

Geometric Dimension & Tolerance (GD& T) is a system for defining engineering tolerances. GD&T is very important part of mechanical product design.

GD&T defines degree of accuracy and precision required on controlled feature of part and used to define the allowable variation in form and possible size of individual features allowable variation between features. 


Form Control

Form tolerances are applicable to single (individual) features or elements of single features. Form…

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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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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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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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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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Straightness : GD&T Tips SMLease Design


Straightness is a condition where an element of a surface or an axis is a straight line.

Where Straightness is Used

  • Used to control the foam of a line on the surface /  feature
  • Straightness of an axis

No Datum plane is required to define straightness and while defining axis straightness LMC and MMC modifiers can be used

Surface Straightness

It is a 2-Dimensional tolerance which is used to ensure that a part is uniform across a surface or feature. Straightness ca…

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Profile Of a Line Control : GD&T Basics SMLease Design

  • Profile of a line control describes a tolerance zone around any line in any feature.
  • Profile of a line is a 2-Dimensional tolerance range that can be applied to any linear tolerance.
  • Profile of line control : controls size, orientation, location & foam of any feature.
  • Line elements of the surface along the profile must lie within the profile tolerance zone and within a size limiting zone.
  • MMC and LMC are not applicable with profile of line control.
  • Datum Plane can be used to con…

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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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Flatness : GD&T Tips SMLease Design

  • Flatness is a condition that defines the flatness of a surface regardless of any datum feature.
  • Flatness is used to make use required surface is flat without tightening any other dimension.
  • Value of Flatness tolerance is always less than the dimensional tolerance associated with a part feature.
  • No Datum Plane is required.
  • LMC and MMC can be used.

Flatness Representation

Tolerance Zone

Reference surface should lie in between two parallel planes



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