Melt Pipes, Long-Neck Elbows & Honed Tube

01. What these parts are

A pipe that carries melt is a bore job first

A pipe that carries polymer melt is not a pipe you buy off a rack. The bore has to be straight, round and smooth enough that material moves through it without hanging up, and the only way there is to drill the hole deep and true, then hone it to size and finish. We gundrill and hone under one roof in Hillsborough, New Jersey — same floor, same week — so the part never loses its reference between operations.

A melt pipe fails on the inside. A step at a joint, a ridge left by a boring bar, a finish rough enough to grab — any of it holds material long enough to degrade, and then it lets go into the product. Gundrilling keeps the bore on centre down the full length instead of letting it walk. Honing afterwards brings it to size, rounds it up and leaves a finish polymer slides across. Flange faces and bolt patterns are machined to match the pipe, not the other way round.

The same bore work goes into hydraulic and pneumatic cylinder tube, accumulator shells, heat exchanger tube, sleeves and liners. If it is a long hole that has to be right on the inside, it belongs here.

A production run of machined stainless cylinders — bores brought to size and finish on the hone.

CNC turned threaded shafts with keyways. Threading is everyday work here, in every standard form.

A blown film die body with machined side ports and flange — flange faces cut to run true to the bore.

02. Ends, flanges and threads

Every connection style these lines use

Most of a pipe’s trouble is at the ends. We machine the full range of connection styles, and we make them to match what is already bolted to your machine.

ID transitions, blended through

A pipe that steps from one inside diameter to another, blended through the transition so the melt never meets a shoulder. The same treatment goes into elbows and adapters where two different bores have to meet.

Flanges machined from solid

When the part has to be one piece, we machine the flange integral with the pipe out of solid bar. No weld in the joint, nothing to crack or leak at the face, and the bore runs through without an interruption.

Flanges welded or threaded on

Where a welded or threaded flange is the right answer, we do that too — and machine the face and bore after welding, so the face runs true to the bore rather than to wherever the weld pulled it.

Threads of every kind

SAE and Unified, metric, Acme and metric trapezoid — internal and external, single and multi-start. Threading is everyday work in this shop, not something we send out to somebody else.

Tapered and sealing ends

Tapered seats, sealing faces and lands machined and finished so the joint seals tight and leaves no gap for polymer to sit in and degrade.

Made to match what you have

If the flange has to mate to something already in the line, send us the mating part, the bolt pattern or the old piece itself. We will measure it and make the new one fit.

03. What we make

The parts, whatever your plant calls them

Melt pipe, connection pipe, transfer pipe, melt transfer line — different plants, different names, same part. We make all of it, in any standard material from 1018 and 1020 through 4140 HT, stainless and tool steels, up to Inconel.

Melt pipes and connection pipes

Polymer transfer: extruder to die, extruder to melt pump, and down the line. Bored straight, honed smooth, and flanged to your existing face-to-face.

Long-neck elbows

45° and 90°. The neck has to be gundrilled deep and straight before the bend is any use, and the bore then honed so material transfers without a step or a dead spot.

ID transition pipes

One inside diameter stepping to another, blended through so there is no shoulder for material to catch on. Common where an older line meets newer tooling.

Adapters, spool pieces and transfer lines

Extruder-to-die adapters, crosshead adapters, melt pump inlet and outlet piping, transition pieces and spool pieces — flanged, clamped or threaded. Jacketed and heated bodies machined for heater bands, cast-in heaters and thermocouple wells.

Hollow honed shafts

A deep hole drilled on centre, then honed to size and finish so the bore runs true to the outside diameter. Turned and ground on the outside without leaving the building.

Honed tube, honed pipe and cylinder barrels

Honed pipe and tube for hydraulic and pneumatic cylinders, cylinder barrels, accumulator tubes and shells, heat exchanger and process tube, sleeves, liners, bushings and bearing housings. Aircraft components and landing gear parts as well.

04. Capacity

Sizes, tolerances and finishes we work to

Check your pipe against the machines it will run on. If one dimension is outside this list, send the drawing anyway — there is often a way to hold the part that the table does not show.

Bore honing	.060″ to 26″ diameter, lengths to 120″
Gundrilling	to 4″ diameter × 96″ deep
Bore tolerance	±.0001″
Bore finish	32 to 8 RMS, checked on a profilometer
Threads	SAE and Unified, metric, Acme and metric trapezoid — internal and external, single and multi-start
Flanges	machined integral from solid bar, welded on, or threaded on; faces machined after welding
Ends	ID transitions, tapered seats, sealing faces and lands
CNC turning	32″ diameter × 60″ long (Okuma LB4000EX); 14″ × 83″ long (Doosan Puma 300XLY)
Vertical turning	60″ diameter
Between centres	43″ × 170″
Milling	to 157″
Lifting	to 10 tons
Materials	1018 and 1020, 4140 HT, stainless and tool steels, Inconel, titanium

05. When there is no drawing

Reverse engineered off the one that failed

Send us the part

Send the pipe that cracked, the elbow nobody can source, or the piece that was modified in the field years ago and matches no drawing on file. We work from the part itself.

Measured, not guessed

Every feature is measured with a Keyence portable CMM, micrometers, bore gauges and ID mics. Where a feature is worn away, we discuss it with you and set the dimension and tolerance from experience rather than from a worn surface.

Obsolete and discontinued sizes

When the original supplier no longer makes the part, or the answer from the OEM is a whole new line, we make the piece you actually need. More on reverse engineering.

Certs, reports and NDAs

Material certifications, dimensional inspection reports and first article inspection supplied on request. We will sign a non-disclosure agreement to protect your drawings and designs. Zala Machine Co. is ITAR registered.

Melt Pipes, Elbows and Honed Bores

Pipe and tube work from the floor. Gundrilled, honed, flanged and threaded in Hillsborough, Somerset County, and shipped to plants through New Jersey, eastern Pennsylvania, New York and New England — Bridgewater, Somerville, Flemington, Edison, Piscataway, Trenton and the rest of the Route 22 and 287 corridor. Parts go out across the United States, Canada and Mexico, and plenty still get dropped off and collected by hand.

06. Common questions

Melt pipes and honed tube: common questions

What is a melt pipe?

A melt pipe carries molten polymer between parts of an extrusion line — extruder to die, extruder to melt pump, or down the line to the next station. Different plants call the same part a connection pipe, a transfer pipe or a melt transfer line. The bore has to be straight, round and smooth enough that material moves through without hanging up and degrading.

Do you make long-neck elbows?

Yes, 45° and 90°. The neck is gundrilled deep and straight before the bend is any use, and the bore is then honed so polymer transfers without a step, a ridge or a dead spot. Both operations happen in this building, so the part keeps its reference from one to the next.

Can you make an ID transition pipe?

Yes. We machine pipes that step from one inside diameter to another, blended through the transition so the melt never meets a shoulder. The same applies to elbows and adapters where two different bores have to meet.

What connection styles and threads can you make?

Flanged, threaded or welded. Flanges are machined integral from solid bar, welded on, or threaded on — and when they are welded, the face and bore are machined after welding so the face runs true to the bore. Threads cover SAE and Unified, metric, Acme and metric trapezoid, internal and external. We also machine tapered seats and sealing ends.

What bore sizes, tolerances and finishes can you hold?

Bores from .060″ to 26″ diameter and lengths to 120″, gundrilled to 4″ diameter and 96″ deep. Internal diameters are held to ±.0001″, with finishes from 32 RMS down to 8 RMS, checked on a profilometer.

Can you match our existing pipe without a drawing?

Yes. Send the part, the mating flange or the bolt pattern and we will measure it and make the new one fit. A good share of this work arrives as a broken part rather than a print.

Do you only do polymer work?

No. The same gundrilling and honing goes into hydraulic and pneumatic cylinder tube, cylinder barrels, accumulator tubes and shells, heat exchanger and process tube, sleeves, liners, bushings and bearing housings. We have honed aircraft components and landing gear parts as well.

What materials do you work in?

Standard stock through to the difficult ones: 1018 and 1020, 4140 HT, stainless and tool steels, and Inconel. Tell us the material with the RFQ and we will source it, or machine stock you supply.

Melt Pipes, Long-Neck Elbows and Honed Tube