Smart Bar Puller


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Smart Bar Puller Competitive Analysis

Today`s competitive environment demands minimizing set-up time and labor saving. When turning parts in quantities of few thousands or more, using a bar feeder makes commercial sense. However, in midrange quantities, it is more economical to use bar puller. Ease of use and reliability are the main advantages of the Smart Bar puller solution.

There are various bar puller concepts. The main problem with bar Pullers is slippage when working with heavy stock diameter and hard materials. Few manufactures preload their pullers jaws with enormous spring force but even this still will not ensure 100% reliability since the pulling force depends on stock hardness, the coefficient of friction that changes because of oil/emulsion etc. Employing high force is not good for the spindle bearings and anyway the serrated jaws damage the outside stock diameter.

We, at Micron addressed these issues as following:

Small diameter/light stock turning

For small diameter/light parts, friction is sufficient to pull the stock material applying a reasonable amount of force.

Large diameter/heavy stock turning

For large diameter parts turning, that usually takes longer run time, our solution is to make a minor groove, 0.5mm (0.02") deep. This way we increase reliability while protecting spindle bearings. In the case that the final part outside diameter (OD) is the stock size, 2-3 additional face cuts are needed to clean the groove.


Disadvantages of competitive pullers and advantages of the Smart Bar Puller:


Disadvantages of pullers based on serrated jaws which enter the material from the side:

1) The serrated jaws are mounted on a flexure beam. There isn’t any protection in case that the jaws are improperly adjusted for the stock diameter. The jaws might bend/deflect beyond the elastic region which will cause damage → Now, go and buy a new one :-(

2) The stock material needs to protrude significantly since their jaws are wide. This is problematic for small diameter turning.

3) Adjustment of diameter is inconvenient, not continuous, requires tools and takes too long.

4) Concentricity between the pullers jaws and the stock diameter is very sensitive.

5) Much more expensive than Micron Smart Bar Pullers.

Disadvantages of pullers based on emulsion/air operation:

1) They depend on emulsion pressure that sometimes drops and in any case they need few seconds for pressure build up.

2) Reliability is not as good as “all mechanical solution”

3) They are too long and too wide which is not comfortable for small CNC lathes

Disadvantage of pullers that are built like slotted collets

1) They are sensitive to concentricity relative to stock diameter and to diameter variation.

2) They need different collet size for each stock diameter.

3) They tend to catch metal particles and if this happens, they will over-flex and get damaged.

4) They need long distance clamping which is problematic for small diameter turning.


Advantages of Smart Bar Pullers

1)    Fast and easy set up.

2)   Continuous diameter and force adjustment, depending on stock size and hardness.

3)   Compact design minimizes tool interference, great for use with small CNC lathes.

4)   Made from Steel and Stainless Steel parts, The 3 jaws are hardened steel self-centered.

5)   Less expensive than competition price.


 Smart Bar Puller Program example for Fanuc 

All numbers on this example program are shown on the attached drawing (picture on top)


Parts counting loop:

#500=0   (Parameter for parts counter)

#501=11 (Number of parts minus 1, on this example we are pulling 11-1= 10 parts)

N1 (counter start)

#500=#500+1 (Counter)

IF[#500LT#501]GOTO10    (Condition number 1 which send you to N10)

IF[#500GE#501]GOTO999  (Condition number 2 which send you to N999)


Start with your single part program:

N10 (beginning of single part program)


xxxxxxxxxxxxxxxxxxxxx (this is your last command before the cutting operation)

Cutting ….

M9 (stop coolant)

M5 (stop spindle)

M19 (spindle orientation) ---------- (just if you are working on Hexagonal bar, you need spindle orientation. In this case you need to tighten the Smart Bar Puller so that it will clamp the bar on the Hexagonal flat surface)

G28 W0 (go to home on "z") --------- (this is just safely clearance)

G28 U0  (go to home on "x") --------- (this is just safely clearance)

M98P57 (call for subroutine number 57------Bar Puller subroutine)

GOTO1 (counter start)


G28 W0 (go to home on "z") --------- (this is just safely clearance)

G28 U0  (go to home on "x") ----------(this is just safely clearance)

M2 (End of program)


Bar Puller Subroutine:

:0057(Bar puller subroutine)

G28 W0 (go to home on "z") --------- (this is just safely clearance)

G28 U0  (go to home on "x") ----------(this is just safely clearance)

M01 (optional stop)

N1G98G97G40T0909  (T0909---- call tool number 9  and offset number 9  which is the bar puller. You have to take offset for the bar puller as for each tool. The offset is to the front of the 3 jaws)

G0 Z15. X0. (Move bar puller to X0 and 15 mm from the original material length)

(This value is a safety clearance relative to the front of the part and you can change it)

G1 Z2. F1000 (Move bar puller towards the rest material. This is still outside the rest material)

G1Z-32. F1000  (Move bar puller into the rest material L=20(part length), C=2 (Cutting tool), E=10 (Bar puller entrance to the material), 20+2+10=32)

M10 (open chuck jaws)

G04X1.5 (wait 1.5 sec to the chuck opening. This time depends on your chuck operation) 

Z-9.F500 (pull the material out to the new cycle start position). Pulling distance has to be calculated, see drawing, on this example, it pulls out the bar 23 mmfrom -32 to -9

M11 (close chuck jaws)

G04X1.5( wait 1.5 sec to the chuck closing. This time depends on your chuck operation) 

G1Z20.F2000 (retract the bar puller from the material)





M99 (End of subroutine)