G00 Rapid Traverse

G00  is the basic G-code for CNC programming. It is used to perform rapid traverse

That mean we always want to make a tool to a position that we want fastly

When you finish one cutting on your part is one position, and you need to move you cutting tool to

the next cutting position, you often use G00 to move tool fastly to the place you wanted.

#NOTE:-you can't use G00 when you're cutting the material of your part. G00 is used to save your time not for cutting.its just for positioning your tool in a quick manner.

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AUTOMATION AND ITS TYPES CAD/CAM

Automation of production systems can be classified into three basic types:

1. Fixed automation (Hard Automation)

2. Programmable automation (Soft Automation)

3. Flexible automation.

1. Fixed automation (Hard automation): Fixed automation refers to the use of special purpose equipment to automate a fixed sequence of processing or assembly operations. Each of the operation in the sequence is usually simple, involving perhaps a plain linear or rotational motion or an uncomplicated combination of two. It is relatively difficult to accomodate changes in the product design. This is called hard automation.

Advantages:

1. Low unit cost

2. Automated material handling

3. High production rate.

Disadvantages:

1. High initial Investment

2. Relatively inflexible in accommodating product changes.

2. Programmable automation (Soft automation): In programmable automation, the production equipment is designed with the capability to change the sequence of operations to accomodate different product configurations. The operation sequence is controlled by a program, which is a set of instructions coded. So that they can be read and interpreted by the system. New programs can be prepared and entered into the equipment to produce new products.

Advantages:

1. Flexible to deal with design variations.

2. Suitable for batch production.

Disadvantages:

1. High investment in general purpose equipment

2. Lower production rate than fixed automation.

Example: Numerical controlled machine tools, industrial robots and programmable logic controller.

3. Flexible Automation:  Flexible automation is an extension of programmable automation. A flexible automation system is capable of producing a variety of parts with virtually no time lost for changeovers from one part style to the next. There is no lost production time while reprogramming the system and altering the physical set up.

Advantages:

1. Continuous production of variable mixtures of product.

2. Flexible to deal with product design variation.

Disadvantages:

1. Medium production rate

2. High investment.

3. High ‘unit cost relative to fixed automation.

ADVANTAGES AND DISADVANTAGES OF WELDED OVER RIVETED JOINTS

      

 

 

    Advantages:

• The welded structures are usually light in weight compared to riveted structures. This is due to the reason, that in welding, gussets or other connecting components are not used.

• The welded joints provide high efficiency, which is not possible in the case of riveted joints.

• Alterations and additions can be made easily in the existing structures.

• Welded structures are smooth in appearance, therefore it looks pleasing.

• A welded joint has a great strength. Often a welded joint has the strength of the parent metal itself.

• It is easily possible to weld any part of a structure at any point. But riveting requires enough clearance.

• The process of making welding joints takes less time than the riveted joints.

• Shape like cylindrical steel pipes can be easily welded. But they are difficulty for riveting.

• The welding provides very strong joints. which can’t be bended easily. This is in line with the modern trend of providing rigid frames.

• In welded connections, the tension members are not weakened as in the case of riveted joints.

    Disadvantages:

• For making weld joints using weld symbols requires a highly skilled labour and supervision.

• Since there is an uneven heating and cooling in welding process during fabrication, therefore the members may get distorted or additional stresses may develop.

• Since no provision is kept for expansion and contraction in the frame, therefore there is a possibility of cracks developing in it.

• The inspection of defects in welding work is more difficult than riveting work.

DESIGN OF SHAFTS

PURE TORSION

when the shaft is subjected to pure torsional load,the diameter of the shaft may be obtained by using torsion equation


                              τ = T r / J

where,
τ=  torsional shear stress
T= torque acting upon the shaft
r = radial distance of the outermost fibre
J = polar moment of inertia

Note:-

The "Polar Moment of Inertia of an Area" is a measure of a beam's ability to resist torsion. The "Polar Moment of Inertia" is defined with respect to an axis perpendicular to the area considered. It is analogous to the "Area Moment of Inertia" - which characterizes a beam's ability to resist bending - required to predict deflection and stress in a beam.

"Polar Moment of Inertia of an Area" is also called "Polar Moment of Inertia", "Second Moment of Area", "Area Moment of Inertia", "Polar Moment of Area" or "Second Area Moment".


        τ=16T/πd^3

∵      J= (π/32)*d^4

         r=d/2




FOR HOLLOW SHAFT JUST REPLACE D^4 WITH [d⁴₀-dᵢ⁴]

where ,

d⁴₀ =outer dia
dᵢ⁴ = inner dia

Calculating the section modulus

To calculate the section modulus, the following formula applies:

An equation: Z = I /y.  

where I = moment of inertia,
           y = distance from centroid to top or bottom edge of the rectangle, here d/ 2. 

For symmetrical sections the value of Z is the same above or below the centroid.

For asymmetrical sections, two values are found: Z max and Z min.

To calculate the value of Z for a simple symmetrical shape such as a rectangle:

An equation: Zxx = I xx/y.  where An equation: Ixx = bd3/12 mm4.

and y=d/2

This gives the formula for  Z = bd2/6 mm3.