|
Ways to Justify A Winslow
Drill Grinding Machine |
|||||
Note: The examples presented here are uniquely independent. When testing your sample ground drills, each drill situation will present different machining conditions. Therefore, any or all of the following examples could apply. Workpiece has eight holes, each 7/8” dia., 1-5/16” deep. |
|||||
| A. Reduced Center Drilling | |||||
| A conventionally pointed drill will “walk” | |||||
| upon part contact. A Winslow-Helical or | |||||
| Bickford Point will center itself upon contact. |
|
Typical
|
YOUR
|
YOUR
|
|
| Typical savings include the elimination of |
Typical
|
Helical
|
Current
|
Tested
|
|
| separate center drilling operations. |
Example
|
Point
|
Application
|
Results
|
|
| Center drilled holes/part |
8
|
0
|
|||
| x Minutes to center drill (5 sec) |
x 0.08
|
x 0.08
|
|||
| Minutes of center drilling part |
0.64
|
0
|
|||
| x Total parts/lot |
x 25,000
|
x 25,000
|
|||
| Center drilling minutes/lot |
16,000
|
0
|
|||
| Center drilling minutes saved/lot |
0
|
16,000
|
|||
|
|
|||||
| B. Increased Feedrates | |||||
| Refer to recommended feedrate charts. | |||||
| Helical or Bickford Points often permit | |||||
| faster feedrates. Typical savings include | |||||
| increased productivity (more parts per hour); |
|
Typical
|
YOUR
|
YOUR
|
|
| faster payback/higher return on capital investment |
Typical
|
Helical
|
Current
|
Tested
|
|
| (maximum use of machine tool capabilities). |
Example
|
Point
|
Application
|
Results
|
|
| Feedrate (IPR) |
.016
|
.022
|
|
|
|
| x Spindle speed (RPM) |
x 350
|
x 350
|
|
|
|
| Feedrate (IPM) |
5.6
|
7.7
|
|
|
|
| Total depth drilled/part (inches) |
1.31
|
1.31
|
|
|
|
| ÷ Feedrate IPM |
÷ 5.6
|
÷ 7.7
|
|
|
|
| Minutes of drilling/part |
0.23
|
0.17
|
|
|
|
| x Total parts/lot |
x 25,000
|
x 25,000
|
|
|
|
| Drilling minutes/lot |
5,750
|
4,250
|
|
|
|
| Drilling minutes saved/lot |
0
|
1,500
|
|
|
|
|
|
|||||
| C. Reduced Reaming | |||||
| Conventionally pointed drills typically | |||||
| will cut .005” to .008” oversize. Winslow- | |||||
| Helical or Bickford Points typically will cut |
|
Typical
|
YOUR
|
YOUR
|
|
| within .002” of drill diameter. Typical savings |
Typical
|
Helical
|
Current
|
Tested
|
|
| include elimination of reaming operations. |
Example
|
Point
|
Application
|
Results
|
|
| Reamed holes/part |
5
|
0
|
|
|
|
| x Minutes to ream (8 sec) |
x 0.13
|
x 0.13
|
|
|
|
| Minutes of reaming/part |
0.65
|
0
|
|
|
|
| x Total parts/lot |
x 25,000
|
x 25,000
|
|
|
|
| Reaming minutes/lot |
16,250
|
0
|
|
|
|
| Reaming minutes saved/lot |
0
|
16,250
|
|
|
|
|
|
|||||
| D. Reducing Deburring | |||||
| A properly ground drill will create less burr. | |||||
| A Bickford Point on most materials will shear | |||||
| off exit burrs within assembly tolerances. | |||||
| Typical savings are found when drilling internal | |||||
| through-holes, intersecting holes and |
|
Typical
|
YOUR
|
YOUR
|
|
| difficult-to-deburr holes (separate deburring |
Typical
|
Helical
|
Current
|
Tested
|
|
| operations can be eliminated). |
Example
|
Point
|
Application
|
Results
|
|
| Deburred holes/part |
8
|
0
|
|
|
|
| x Minutes to deburr by hand (3 sec) |
x 0.05
|
x 0.05
|
|
|
|
| Minutes of deburring/part |
0.40
|
0
|
|
|
|
| x Total parts/lot |
x 25,000
|
x 25,000
|
|
|
|
| Deburring minutes/lot |
10,000
|
0
|
|
|
|
| Deburring minutes saved/lot |
0
|
10,000
|
|
|
|
|
|
|||||
| E. Reduced Tool Changes | |||||
| Longer tool life results in fewer tool | |||||
| changes on any machine. Beyond that, | |||||
| multiple-spindle applications and transfer | |||||
| machines require longer tool change time |
|
Typical
|
YOUR
|
YOUR
|
|
| due to presetting. Typical savings are |
Typical
|
Helical
|
Current
|
Tested
|
|
| found in dedicated-machine applications. |
Example
|
Point
|
Application
|
Results
|
|
| Tool change time/drill (minutes) |
3
|
3
|
|
|
|
| x Number of spindles |
x 8
|
x 8
|
|
|
|
| Total tool change (minutes) |
24
|
24
|
|
|
|
| x Number of drill changes/lot |
x 25
|
x 2
|
|
|
|
| Total tool change minutes/lot |
600
|
48
|
|
|
|
| Total change minutes saved/lot |
0
|
552
|
|
|
|
|
|
|||||
| F. Reduced Regrinding | |||||
| Regrinding time can be saved in two ways: | |||||
| The first is through less grinding because | |||||
| of longer tool life. The second is the reduced | |||||
| amount of stock that has to be ground | |||||
| off of a Helical- or Bickford-pointed | |||||
| drill to recondition the point, as | |||||
| compared to a split or notched point. |
|
Typical
|
YOUR
|
YOUR
|
|
| Savings include lower drill inventory |
Typical
|
Helical
|
Current
|
Tested
|
|
| as well as less actual regrinding time. |
Example
|
Point
|
Application
|
Results
|
|
| Number of parts in lot |
25,000
|
25,000
|
|
|
|
| ÷ Number of holes/drill change |
÷ 1,000
|
÷ 12,500
|
|
|
|
| Number of drill changes/lot |
25
|
2
|
|
|
|
| x Number of drills/drill change |
x 8
|
x 8
|
|
|
|
| Number of drills used/lot |
200
|
16
|
|
|
|
| x Regrind minutes/drill |
x 3
|
x 3
|
|
|
|
| Typical regrind minutes/lot |
600
|
48
|
|
|
|
| Regrind minutes saved/lot |
0
|
552
|
|
|
|
|
|
|||||
| G. Total Minutes Saved Per Lot of Parts | |||||
|
Typical
|
|
YOUR
|
|||
|
Helical
|
|
Tested
|
|||
|
Point
|
|
Results
|
|||
| A+B+C+D+F (minutes) |
|
44,854
|
|
|
|
| x Burden rate ($/minute @ $120/hour) |
|
x $ 2
|
|
|
|
| Total $ savings/lot |
|
$ 89,708
|
|
|
|
| x Number of lots this size processed/year |
|
x 3
|
|
|
|
|
|
|
|
|
||
| Total $ Savings/Year |
|
$ 269,124
|
|
|
|
|
|
|||||
| Click here for a PDF file of this Justification Chart | |||||
|
|
|