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Tuesday, 20 November 2018

G AND M-CODES FOR CNC MACHINES

CNC G codes
G00 - Rapid traverse; Mill and Lathe
G01 - Linear interpolation (machining a straight line); Mill and Lathe
G02 - Circular interpolation clockwise (machining arcs); Mill and Lathe
G03 - Circular interpolation, CCW Polar co-ordinates; Mill and Lathe
G04 - Dwell time; Mill and Lathe
G09 - Mill and Lathe, Exact stop
G10 - Polar co-ordinates linear interpolation; Mill and Lathe
G12 - Circular pocket milling, clockwise; Mill
G13 - Circular pocket milling, counterclockwise; Mill
G14 - Exact spindle stop
G17 - X-Y plane for arc machining; Mill and Lathe with live tooling
G18 - Z-X plane for arc machining; Mill and Lathe with live tooling
G19 - Z-Y plane for arc machining; Mill and Lathe with live tooling
G20 - Inch units; Mill and Lathe
G21 - Metric units; Mill and Lathe
G27 - Reference return check; Mill and Lathe
G28 - Automatic return through reference point; Mill and Lathe
G29 - Move to location through reference point; Mill and Lathe (slightly different for each machine)
G31 - Skip function; Mill and Lathe
G32 - Thread cutting; Lathe
G33 - Thread cutting lead constant; Mill
G34 - Thread cutting lead increasing; Mill
G35 - Thread cutting lead decreasing; Mill
G40 - Cancel diameter offset; Mill. Cancel tool nose offset; Lathe
G41 - Cutter compensation left; Mill. Tool nose radius compensation left; Lathe
G42 - Cutter compensation right; Mill. Tool nose radius compensation right; Lathe
G43 - Tool length compensation; Mill
G44 - Tool length compensation cancel; Mill (sometimes G49)
G50 - Set coordinate system and maximum RPM; Lathe
G52 - Local coordinate system setting; Mill and Lathe
G53 - Machine coordinate system setting; Mill and Lathe
G54~G59 - Workpiece coordinate system settings #1 t0 #6; Mill and Lathe
G61 - Exact stop check; Mill and Lathe
G65 - Custom macro call; Mill and Lathe
G70 - Finish cycle; Lathe
G71 - Rough turning cycle; Lathe
G72 - Rough facing cycle; Lathe
G73 - Irregular rough turning cycle; Lathe
G73 - Chip break drilling cycle; Mill
G74 - Left hand tapping; Mill
G74 - Face grooving or chip break drilling; Lathe
G75 - OD groove pecking; Lathe
G76 - Fine boring cycle; Mill
G76 - Threading cycle; Lathe
G80 - Cancel cycles; Mill and Lathe
G81 - Drill cycle; Mill and Lathe
G82 - Drill cycle with dwell; Mill
G83 - Peck drilling cycle; Mill
G84 - Tapping cycle; Mill and Lathe
G85 - Bore in, bore out; Mill and Lathe
G86 - Bore in, rapid out; Mill and Lathe
G87 - Back boring cycle; Mill
G90 - Absolute programming
G91 - Incremental programming
G92 - Reposition origin point; Mill
G92 - spindle speed limit, Thread cutting cycle; Lathe
G94 - Feed rate, Per minute feed; Mill
G95 - Feed rate, Per revolution feed; Mill
G96 - Constant surface speed control; Lathe
G97 - Constant surface speed cancel
G98 - Per minute feed; Lathe
G99 - Per revolution feed; Lathe

CNC M Codes
M00 - Program stop; Mill and Lathe
M01 - Optional program stop; Lathe and Mill
M02 - Program end; Lathe and Mill
M03 - Spindle on clockwise; Lathe and Mill
M04 - Spindle on counterclockwise; Lathe and Mill
M05 - Spindle stop; Lathe and Mill
M06 - Tool change; Mill
M07 - Flood Coolant on; Lathe and Mill
M08 - Coolant on; Lathe and Mill
M09 - Coolant off; Lathe and Mill
M10 - Chuck or rotary table clamp; Lathe and Mill
M11 - Chuck or rotary table clamp off; Lathe and Mill
M19 - Orient spindle; Lathe and Mill
M30 - Program end, return to start; Lathe and Mill
M97 - Local sub-routine call; Lathe and Mill
M98 - Sub-program call; Lathe and Mill
M99 - End of sub program; Lathe and Mill

What are Numerical Control Machine? What are NC Machines?

          Numerical control, popularly known as the NC’. Numerical control is defined as the form of programmable automation, in which the actions are controlled by the direct insertion of numerical data such as numbers, letters, and symbols. In case of the machine tools, these programmable automation machines are used for the operation.
          In other words, the numerical control machine is defined as a mechanical machine that is controlled by the set of instructions (input information) called as a program via punched paper tapes or magnetic tapes. The name Numerical control is given to this type of programming, since numbers form the basic program instructions. When the type of job changes, the program instructions of the job also change. Writing new instructions for each job is easy, hence NC offers a lots of flexibility in its use and also more economical for producing a single or a large number of parts.
          The NC machines are used in variety of applications like inspection, assembly, sheet metal work etc., but it is mainly used for machining operations like drilling, milling, turning etc.,

The main elements of a NC machine tool are,
1. The control unit, also known as console or director - it sends the command signals to the drive units.
2. The drive units.
3. The position feed back package.
4. Magnetic box - It acts like electrical control cabonet
5. Manual control - To perform functions manually. 

Classification of NC Machine Tools:

          According to various features, NC machine tools are classified as the following
1. According to the type of power to the drives
1. Electrical
2. Hydraulic
3. Pneumatic
2. According to motion control system of slides
1. Point- to – point system -- Used for drilling machines
2. Straight line system -- Used for turning machines
3. Contour (or) continuous path system -- Used for milling machines
3. According to the feedback system
1. Open loop system -- In this system, there is no ‘feed back’ and no return signal to indicate whether the tool has reached the correct position at the end of the operation or not.
2. Closed loop system -- A feed back is built into system, which automatically monitors the position of tool.
4. According to axis identification
1. 2- axis
2. 3- axis
3. 4- axis
4. 5- axis

Method of Listing Coordinates of Points in NC/ CNC System

Coordinates of Points
          Two types of co-ordinate systems are used to define and control the location of the tool in relation to the work piece. Each system has its own applications and the two co-ordinate systems can be used independently or may be mixed within a NC part program based on the machining requirements of the work piece. The co-ordinate systems used are
1. Absolute co-ordinate system and
2. Incremental co-ordinate system.

(a) Absolute Co-ordinate System: In this system the co-ordinates of a point are always referred with respect to one reference point that is, datum. The datum positions in the X-axis, Y-axis and Z-axis are defined by the user / programmer before starting the operation on the machine. A main advantage of using absolute system is that it is very easy to check and fix a program written using this method. If a mistake is made in the value of any dimension in a particular block, it will affect that dimension only and once the error is corrected there will be no further problems.

(b) Incremental Co-ordinate System: In the incremental system the co-ordinates of any point are calculated with reference to the previous point i.e. the point at which the cutting tool is positioned is taken as datum point for calculating the coordinates of the next point to which movement is to be made. It is difficult to check a part program written in incremental dimension mode.

Absolute and Incremental Programming

Point
Absolute system  
Incremental System 
P1
1,3
1,3
P2
3,2
2,-1
P3
4,2
1,0
P4
4,3
0,1

Wednesday, 14 November 2018

CHILLER CAPASITY CALCULATION PROCEDURE

          Just like refrigerator a chiller uses a refrigeration cycle to cool water or dehumidifies air. This chilled water then used to cool a larger space, such as a factory floor or for process uses. Cooling equipment in this matter increases its efficiency by providing a steady thermal environment. Before we begin to derive a chiller's capacity we must know three variables, they are:
1. The incoming water temperature
2. The chilled water (out going water) temperature required
3. The flow rate
          This formula produces the chiller's capacity in British Thermal Units (BTUs). That scale directly corresponds with the more common unit of "tons" that cooling systems often use.
For our example, we will calculate what size chiller is required to cool 60 GPM (gallons per minute) from 64 °F to 52 °F? Use the following five steps and general sizing formula:

1. Calculate Temperature Differential (ΔT°F)
          Subtract the temperature of water as its leaves the chiller from the temperature of the water as it enters it.
ΔT°F = Incoming Water Temperature (°F) - Required Chilled Water Temperature.
· Example: ΔT°F = 64°F - 52°F = 12°F

2. Calculate BTU/hr. (British Thermal Unit/hr)
          The cooling capacity of air conditioners is measured in BTUs, or British thermal units. The more Btu of capacity, the larger the room the air conditioner can cool. Scientifically, one Btu is the amount of energy required to change the temperature of 1 pound of water by 1 degree Fahrenheit. In terms of air-conditioner capacity, the rule of thumb is that it takes around 25 Btu to cool 1 square foot of room floor area.
To calculate BTU Multiply the temperature difference by the flow rate (that what we need), which is measured in gallons per minute. If, for instance,
BTU/hr. = Gallons per hr x 8.33 x ΔT°F
· Example: 60 gpm x 60 x 8.33 x 12°F = 3,59,856 BTU/hr. 
(Or)
· 40 gpm x 500 x 12°F = 3,59,856 BTU/hr.  (since 60 x 8.333 = 500)

3. Calculate tons of cooling capacity
Tons = BTU/hr. ÷ 12,000
· Example: Ton capacity = 239,904 BTU/hr. ÷ 12,000 = 29.998 tons
1 ton = 12000 BTU

4. Oversize the chiller by 20%
 Ideal Size in Tons = Tons x 1.2
· Example: 29.998 x 1.2 = 35.9976

5. You have the ideal size for your needs
· Example: a 35.9976 (or 35-Ton) chiller is required


Monday, 12 November 2018

5S CONCEPT IN INDUSTRIES

Image Credits : GOOGLE
          5S is a regular systematic form of visual management, using everything from floor tape to operation manuals. It not only simply focus on visual order, authentication, hygiene or organisation; It is also about increasing efficiency, profitability, service and safety. 5S is a unique idea and framework that emphasizes the utilisation of a specific mindset and instruments to create efficiency and esteem. The principles underlying a 5S program initially seem to be simple and obvious common sense. However, once implemented in a disciplinary manner, the above benefits will occur.
          This system focuses on keeping everything where it works and keeping the workplace clean, making it easier for people to do their jobs without wasting time, without confusion and without injuries. It involves observing, assessing everything present in a space, collaborating, and searching for waste and also furthermore includes the practice of removing waste, keeping this cycle going organise, clean, repeat.

5S include five Japanese terms that everyone begin with the letter "S".

Credits: Google
What Does 5S Stand For?
          5S, generally stated as 5s or Five S. 5S came from Japanese terms. These Japanese words used to describe the phases of the 5S system of visual management. Each term begins with an S. In Japanese, the 5S's are Seiri, Seiton, Seiso, Seiketsu, and Shitsuke. In English, the 5S's are usually translated as Sort, Set in order, Shine, Standardize, and Sustain.

The Five key practices are as described below:

1) JAPANESE TERM -- Seiri
    ENGLISH TERM    -- Sort
          It involves going through all the tools, materials, equipment etc., keeping solely the essential items needed for the full work.
Some questions that have to raise our self at this stage are:
--> What is the utilisation of this equipment or item?
--> When was the last time this item was used?
--> However typically it is used?
--> Who used it?
--> Do this item really essential to be here?
          This action passes through all subjects in a workplace and work piece to determine the value of each item and ends with the need and removal. Everything that has not been used to complete the work process ought to leave the work area.   

2) JAPANESE TERM -- Seiton
    ENGLISH TERM    -- Set in order
          Once the extra items are removed it is easier to see and identify what is what. Make sure that all items are sorted out and each item has an assigned location. Organise all the remaining items in a logical way and felicitate the work to make the workers complete.  This often involves:
  • Which people (or workstations) use which items?
  • At what point those items are used?
  • what items are often used?
  • Should things be sorted by type?
  • Where would it not be most obvious to place items?
  • Do some appointments on unnecessary movements?
  • Need more storage containers to handle things?

 3JAPANESE TERM -- Seiso
      ENGLISH TERM    -- Shine
          The shine stage of 5S focuses on proactive efforts to keep workplace areas clean and orderly. This means cleaning and maintaining the recently sortedout workspace. It involves simple and routine tasks such as sweeping, moping, wipingdown surfaces, putting tools and materials away etc., In addition to basic cleaning, performing regular maintenance of machinery, tools and other equipment.


 4JAPANESE TERM -- Seiketsu
      ENGLISH TERM    -- Standardize
          After completing first three steps of 5S, things should look pretty good. All the unnecessary things is gone, everything is maintained, spaces are cleaned, and equipment is in good working condition.
          In this stage create a set of standards for both organization and processes. Fundamentally, this is where you take the first three S's and make rules for how and when these tasks will be performed. These standards can involve regular tasks, creating schedules, charts, lists, and posts instructions so these exercises turned out to be standard.


5JAPANESE TERM -- Shitsuke
      ENGLISH TERM    -- Sustain
          Sustain refers to the process of keeping 5S running smoothly, yet in addition of keeping everyone in the assosiation included and involved. Sustain new practices and conduct audits to maintain discipline. This suggests the previous four S's must be continued over time. First of all managers need to participate to give motivation to employes, and make the employees to follow these steps on the manufacturing floor, or in the office. Sustain is about making 5S a long-term program, not only just an event or here and now venture (short-term project). Ideally, 5S turns into a part of an organisation's culture and when 5S is sustained after some time, that's when businesses will begin to see persistent positive outcomes.


6SAFETY -- THE 6th S
          Some companies prefer to include a sixth S in their 5S program i.e., Safety. At that point when safety is included, this framework is often called as 6S. The safety step involves focusing on what can be done to eliminate risks in work processes by arranging things in certain ways.
          Some industries believes Safety a result of performing the other 5S's appropriately, and thus say 6S isn't necessary. They think whether workplace is properly organised and cleaned and uses helpful visual safety cues, a seperate safety step is senseless.
          Neither approach to safety is right or wrong, but however a business needs to approach safety, it ought to bear in mind that paying attention to safety is vital.


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