Skip to main content

Juki 501 vs 502 Nozzle — Which One for 0201 and 0402 Parts

The 501 and the 502 sit next to each other on every nozzle chart, both listed around 0.7 mm, and both get sold as "the small Juki nozzle". They are not the same tip at two sizes. They are two different pick designs with a hard boundary between them, and on a LumenPnP-class machine you will almost always want the 502.

Here is what Juki's own catalogue says, and what it means when you are standing at the machine with a reel of 0201s in one hand and a reel of 0402s in the other.

What the catalogue actually specifies​

Numbers below are from Juki's Nozzle Application Catalogue (Rev C3). The 5xx family is the nozzle type for the 2000-series placement machines (2010 through 2060) and the FX1; it is the family every LumenPnP-based machine borrows its nozzle interface from. Juki lists eight standard 5xx nozzles, 501 through 508.

501502
Tip outer0.7 × 0.4 mm (flat face)⌀0.7 mm
Suctiontwo ⌀0.2 mm holesone ⌀0.4 mm bore
Component width DD < 0.45 mm0.45 ≤ D < 0.75 mm
Juki part no.E36007290A0 / 40001339E36017290A0 / 40001340
Juki's flat-chip row0201 (0.6 × 0.3 mm)0402 (1.0 × 0.5 mm)

The boundary is 0.45 mm, and it is a boundary rather than a preference: Juki's flat-chip table maps 0201 to the 501 and 0402 to the 502, with nothing in between. Note also that 501 and 502 do not overlap, unlike neighbours further up the range — the 503 tops out at 1.45 mm while the 504 starts at 1.1 mm, so those two share a happy zone. There is no shared zone here. A 0402 is not a 501 part on a good day; it is the wrong tip.

The two-hole tip is a different design, not a smaller one​

The obvious assumption is that a 501 is a 502 with less metal on the end. It isn't. The 501's business end is a flat 0.7 × 0.4 mm face with two ⌀0.2 mm holes punched through it, while the 502 is a round ⌀0.7 tip with a single ⌀0.4 bore.

Working the suction area out from those numbers:

  • 501: two holes, area = 2 × π × 0.1² = 0.063 mm²
  • 502: one bore, area = π × 0.2² = 0.126 mm²

Exactly double, because the 502's bore has twice the radius of one 501 hole and there is only one of them. If you have wondered why a 501 sometimes feels weak on a pump that has no trouble with the 502, that is the whole reason — same vacuum, half the aperture to pull through.

Why would Juki design it that way? Because for a 0201 the constraint is the opposite problem. A single aperture large enough to move useful air is also large enough to swallow a 0.3 mm wide chip, or to drag it sideways as the tape releases. Two small holes keep each opening smaller than the part in its narrow direction, while the pair together still moves more air than a single ⌀0.2 hole would. It is a design tuned to one component, not a general-purpose small nozzle.

Where a 501 goes wrong for real​

The tip face tells you the rest. A 501's face is 0.7 × 0.4 mm = 0.28 mm². A 0201 footprint is 0.6 × 0.3 mm = 0.18 mm², so the face covers the whole part with about 0.1 mm of margin on the narrow axis — that is the design working as intended. A 0402 is 1.0 × 0.5 mm = 0.5 mm², nearly twice the face area. There is no straddle. You are picking a part bigger than your nozzle.

What that looks like in practice:

  • Parts picked and then rotated or skidding sideways. With two suction holes either side of the centreline, a part sitting between them can pivot during the Z move. The bottom camera can measure rotation and offset, but a pick that is still settling is a moving target — the measurement is taken before the part has finished moving.
  • Intermittent "no part on nozzle" followed by a part sitting in the tape. Nothing to do with vacuum sensors on a Vertex 4 — see below — this is the tip face never having made clean contact.
  • Small parts fine in the feeder, dropped on the board. A low-flow aperture means less hold for the same vacuum level. For a 0201 that is harmless. For anything heavier it is the difference between a placement and a bruise on the PCB.

Juki's component table has no row anywhere that pairs a 501 with a 0402 or larger. When a reseller chart tells you the 501 is "the small chip nozzle", it is describing which shelf it sits on, not what it can pick.

What this means on a Vertex 4​

The Vertex 4's rated placement range starts at 0402. That is the machine's floor, and 0402 is exactly the 502's job in Juki's table. So the 501's single catalogue application — 0201 — sits below what the machine is rated for, which is why we do not sell a 501.

What the head ships with and what you can add:

PartNozzles includedPrice
Head module kit (dual nozzle)503 + 505$239
Nozzle assembly, single503 assembly (tip, holder, connecting rod, 4 mm pneumatic fitting, 28 mm stepper)$49
Nozzle assembly, pair503 + 505 assemblies$98
Juki-compatible nozzle set 502–507502, 503, 504, 505, 506, 507 (tips only)$69

For fine work, the 502 is the nozzle to add first. The 503 that ships with the head covers 0402 only by overreach — it is one step up from the tip Juki specifies for that chip — and the 502 is the tip built for it.

One Vertex 4 detail worth knowing: the machine does not use a vacuum pressure sensor. Part presence is confirmed by the bottom camera, and the machine relies on that measurement for placement. On a machine with a vacuum sensor, an under-flowing aperture announces itself as a failed pick threshold; here it does not. The 501-on-0402 mistake therefore surfaces later in the cycle, as a part that picks, gets photographed, and ends up slightly off — or as a vision failure on a part that is half-hanging off the tip.

The other thing the vision step cares about is the tip itself. The nozzles we ship are black by default, because a black tip reads much more cleanly in OpenPnP's nozzle tip calibration than bare metal does: a shiny tip bounces the LED rings back at the camera and makes the runout measurements noisier. If you are sourcing nozzles from a general parts supplier, tip appearance is one of the things that quietly changes your calibration quality.

Before you order, check three things​

  1. Measure the part's width, not its length. Juki's limit is stated in terms of the minimum width or diameter D. A 0402 is 1.0 mm long but only 0.5 mm wide, and 0.5 is the number that decides the nozzle.
  2. Buy by Juki part number, not by the dimension column. Vendor charts are inconsistent about the 5xx family: the same listing format shows "501 ASSY 0.7 × 0.4" alongside a 500 with the same 0.7 × 0.4 description, and at least one chart describes the 501 tip as a single ⌀0.25 hole where Juki's catalogue specifies two ⌀0.2 holes. The part numbers E36007290A0 / 40001339 (501) and E36017290A0 / 40001340 (502) are the unambiguous identifier.
  3. Do not cross generations. 5xx nozzles belong to the 2000-series machines; the 1xx and 2xx nozzles belong to the older 750/760 heads. Similar-looking tip dimensions across those families do not make them interchangeable on your machine.

After the swap​

Every nozzle number has a different tip length, so changing from a 501 to a 502 moves your pick height. Re-run the nozzle tip runout calibration with the bottom camera, then verify pick height on a real part before starting a job — skipping that step is the usual reason a swap "breaks" a machine that was working five minutes earlier.

If a pick is failing right now, work backwards: measure the part's narrow dimension, check it against the nozzle in the spindle, and only then look at vacuum tubing. And if your smallest part is 0.5 mm wide, stop reading about the 501 — the 502 is the tip you want.