Why use plastic?
There are three kinds of plastic needles:
1) a plastic hub and a stainless tube
2) a conical plastic nozzle
3) Teflon tube
These are cheap, and disposable. They are the answer for hand dispensing. The Teflon for Cyanoacrylates that will ruin metal and ceramic nozzles. Cyanoacrylates ruin the plastic too, but who cares – throw it away and get a new one – it costs pennies. For hand dispensing – the eye can adjust and the variations may not matter.
Where the plastic falls down is in consistency and precession. Plastic flexes and moves during the dispense. In course (low precision) applications – it does not mater, but in areas where automatic equipment is used this is not a good characteristic. It also wears – abrasive materials wear the plastic quickly.
Standard color - vs size matrix:
|Color||Gage||Outlet in mils (1/1000 of an inch)||Outlet in mm||Color||TARGET DOT OR LINE WIDTH|
126 - 189 mils
3.2 - 4.8 mm
112 - 168 mils
2.9 - 4.3 mm
98 - 147 mils
2.5 - 3.8 mm
66 - 99 mils
1.7 - 2.5 mm
48 - 72 mils
1.2 - 1.8 mm
40 - 60 mils
1 - 1.6 mm
32 - 49 mils
0.8 - 1.2 mm
0.7 - 1 mm
20 - 30 mils
0.5 - 0.8 mm
16 - 24 mils
0.4 - 0.6 mm
The variations have different uses:
|Example||Total Length||Needle Type||Recommended use|
Reaches into confined spaces, used for very low viscosities where large surface area on the needle is desirable.
This is not a good choice for filled materials or very thick materials because the long narrow needle. If one needs to reach into a confind space with such a material - a larger opening will often be required.
Some bend these to creat a curve - This often creates a pintch point and results in clogging. Some prebent nozzles are available on request.
|1 ¼”||Stainless||Mid length, can still reach into some confined areas, but creats much less backpressure and resists clogging more than a longer needle. This is a compromise
Normal, use this for all applications not requiring special handling.
The shorter needle barrel creates less backpressure, less clogging and is more desirable than the above in most applications. This is probably the correct choice, except when there is a reach or obstruction issue where a longer needle is required.
Short needle results in: less clogging, faster dispense
|1 ¼"||Plastic Conical||
Normal for high viscosity fluids, great when a needle gets clogged or where the pressure is too high for the needle
This is the best choice for high viscosity materials are used. It has the lowest backpressure and the fastest dispense. It have a cople of weaknesses: It is not a good choice for automatic machines where accuracy is required. As the prssures of a dispense are applied, the plastic flexes changing the X-Y offset. When dispensing be hand, this is not a factor
|1 ¼"||Teflon w/ Stainless Steel stiffener||Used for glue and adhesive that reacts with metals, the stainless needle is a stiffener and does not contact the fluid|
|1 ¼"||Teflon||Used for glue and adhesive that reacts with metals - if tip position is effected by bending - use the stiffener offered above|
What Dispense Tip is the Right One?
Dispense Tip Sample Kit
This kit has 2 cases; the larger case has 2 empty 5cc syringes, 2 empty 10cc syringes, 2 empty 30cc syringes, all with thumb plungers ready for fluid loading, and a smaller case. There is a lot of space to store additional dispense tips, plus the unused dividers to reconfigure the case. This case is idea for storage in a drawer, or workbench.
The smaller case has 12 types of dispense tips, with 5 of each type. The case fits in most pockets and has a hand strap for carrying it with you.
This kit is designed as an evaluation kit – It allows the user to try a number of dispense tips and then order a larger quantity of only what is suitable for the user’s specific application.