Gentlemen,

How do you determine the diameter of a closing die in front of a double twist buncher? Our old bunchers are set up to allow the wire to travel directly into the machine without an eyelet plate or closing die. Our results are satisfactory even though this is probably not the best pratices.

Recently, we purchased a used double twist buncher. The manufacturers documentation makes no reference to the opening size of the closing die.

Some of our wire constructions are bunched with an odd number of wire ends. How do you determine the finished diameter? Once the theoretical diameter is determined, how much larger is the die opening?

Ex: Annealed copper wire - .080" diameter x 4 ends
Or aluminum wire - .072" diameter x 5 ends

Please explain how to determine the size of the closing die from the information above.

Thanks in advance for your help,

Raoul

Hi Raoul,

The theoretical diameter of the stranded conductors going through the die is mathematically determined.

No. wires Construction multiplier
2 2 2
3 3 2.16
4 4 2.42
5 5 2.7
6 6 around a dummy core 3
7 1 center, 6 around 3
8 1 center, 7around 3.33
10 2 center, 8 around 4
12 3 center, 9 around 4.16
14 4 center, 10 around 4.42
15 5 center, 10 around 4.7
16 5 center, 11 around 4.7
17 1 center, 6 around, 10 around 5
18 1 center, 6 around, 11 around 5
19 1 center, 6 around, 6 around 5

Please note that the 19 wire construction can also run as a smooth, round unilay construction, using a shorter lay. The multiplier is then 4.8736

The die diameter is 2% larger than the calculated no.

If you have further questions you can contact me directly.


Best Regards,

Willy Hauer
www.Howarequipment.com

Hi Willy,

Thank you so much for taking the time and effort to share this information.

Best regards,

Raoul

Good day..

I saw your calcs and I'm wondering How to determine the multiplier to go beyond the 19 strands, we currently go up to 105 ends on a double and single twist bunchers/closers, any reading material on this subject available?
Thankyou

Greetings from Toronto,

Your question cannot be answered with a simple formula. As a matter of fact the diameters vary even between single and double twist operations and are also dependent on the actual lay length.

Below is a table which shows the various factors for different geometric formations.

The bunch diameter on a double twist will be approximately 10 – 12% larger and on the Single twist 2 – 5% larger.

This should at least give you a starting point.

n f n f n f
1 1.00 19 5.00 61 9.00
2 2.00 24 6.00 70 10.00
3 2.15 26/27 6.15 75 10.15
4 2.41 28/30 6.41 80 10.41
5 2.70 31/32/33 6.70 85 10.70
7 3.00 37 7.00 91 11.00
10 4.00 44 8.00 102 12.00
12 4.15 48 8.15 108 12.15
14 4.41 52 8.41 114 12.41
16 4.70 56 8.70 120 12.70

I remember that Fred Krafft (Cook Machinery) wrote an article decades ago, covering this subject. Unfortunately I lent my copy to someone and never got it back. Maybe someone can remember this article and get us a link.


Best Regards,

Willy

www.HowarEquipment.com

Willy,
I asked a couple of weeks ago about Fred. He knew a lot about wire manufacturing and was a fixture at the Wire Association meetings for a long time.

Richard/Spectre