How do I select the length of the JO-96 active electrode for the material width and machine geometry?

Active length without guesswork. How do I fit the JO-96 electrode into the web width and layout of the machine?

The selection of the length of the active ionising electrode (e.g. JO-96) must not be random. It must cover the entire width of the material with allowance for edge "snaking" and take into account the mounting distance and machine obstructions. Below you will find a simple algorithm, "on a napkin" patterns, examples and the most common mounting pitfalls.

What parameters do you need to know before ordering?

• What is the material's working width (W) and maximum edge 'float' (±E)?

  Measure the width at the point of deionisation and maximum edge deviations (guiding/oscillation of rollers).

• At what distance (d) from the web surface will you mount the electrode?

  Realistic distance after taking into account guards, beams and safety - typically 50-150 mm.

• Will you use a strip alone or a strip with an ionised blower?

  Blowing increases the 'range' and helps with longer distances or high speeds.

• Do you have mounting restrictions and shading by rollers/frames?

  Identify the zones that 'obscure' the edges - this will influence the length reserve needed.

Selection rule - how much stock per site do you need?

• How to calculate the minimum active length L_active?

  Use the formula:
  L_active = W + 2 × M, where M = M_edge + M_div.

• What is M_edge stock?

  M_edge = max(20-30 mm, E) - minimum fixed allowance on each side, greater of: typical allowance of 20-30 mm or measured 'float' of the E edge.

• What is the M_div dispersion stock and what does it depend on?

  This is the overdispersion due to the propagation of the ion flux with distance. Assume the angle of effective dispersion θ:
  - non-blowing strip: θ ≈ 12-18°
  - air strip/curtain: θ ≈ 25-35°
  Design: M_div ≈ d × tan(θ).

Machine geometry - how to set up and 'add' a layout?

• Should the slat be parallel to the axis of the cylinder?

  Yes - parallel mounting gives an even distance across the width. Slanted mounting results in one edge being closer (over-ionised), the other further away (under-ionised).

• Does the distance to metal components matter?

  Yes - keep a distance of at least a few tens of mm from earthed components (frame, cowl) so that they do not 'pull' ions off the edge.

• Can the position relative to the cylinder 'shade' the edges?

  Yes - if the slat is too close to the roller face, the edges of the web may be shielded. Then increase the stock M or move the slat over the free web.

Quick calculation examples - how to select L_active in practice?

• Example 1: 1200 mm wide, d = 100 mm, without blowing, E = 10 mm - how much L_active?

  Assume θ = 15°. M_div = 100 × tan(15°) ≈ 27 mm. M_edge = max(25, 10) = 25 mm. M = 25 + 27 = 52 mm. L_active = 1200 + 2×52 = 1304 mm. Order your next longer active length (e.g. ~1300-1350 mm).

• Example 2: 1600 mm wide, d = 150 mm, with blowing, E = 15 mm - what length?

  Assume θ = 30°. M_div = 150 × tan(30°) ≈ 87 mm. M_edge = max(25,15)=25 mm. M = 112 mm. L_active = 1600 + 2×112 = 1824 mm. Consider a strip of ~1850-1900 mm or two sections 2×950 mm.

• Example 3: 800 mm wide, d = 70 mm, E = 8 mm, without blowing - what to choose?

  θ = 15°. M_div ≈ 70 × tan(15°) ≈ 19 mm. M_edge = 20 mm. M = 39 mm. L_active ≈ 800 + 2×39 = 878 mm → select ~900 mm.

Specifics of models with "active length" and "total length" - What to ask the supplier?

• Does the order length refer to the ionising part or the whole beam?

  In many systems (including JO-96) it is stated separately active length (needle/emitter zone) and overall length (with fronts, connectors). Always confirm, which You declare the value when ordering.

• Are length jumps or modular sections available?

  Often the lengths are produced in specific increments (e.g. every few tens of mm) or as combined modules. Narrow machines are easier to handle with a single beam, very wide machines with sections.

Line speed vs length - will length alone solve the problem?

• With very fast lines, is it sufficient to extend the strip?

  Not always - neutralisation time must be shorter than the residence time of the web in the ion zone. At high speeds, amplify the effect with blowing or use two slats in series.

• Do two slats one after the other make sense?

  Yes - a second slat 150-300 mm behind the first extends the effective zone (better effect at high speeds and higher d).

Width distribution - how to avoid 'dead edges'?

• Is one slat on top enough?

  If loads return after contact with rollers or lamination, consider deionisation of both sides webu.

• How to deal with a very wide web (>1.8-2.0 m)?

  Use modules (e.g. 2-3 sections) with an overlap of 20-40 mm between zones and a uniform distance d across the width.

Checklist for ordering and installation - what to take care of?

• Have you confirmed L_active according to the design and installation conditions?

  Enter W, E, d, θ and recalculate L_active; round up to the available dimension.

• Do you have an assembly drawing with shield and roller spacers?

  Select the shading and offset from the cylinder heads.

• Have you made provision for service access to the emitters?

  Minimum of one side available for cleaning; plan hygiene schedule.

Common mistakes - what to avoid?

• Is "to the point" equal widths of fabric a good idea?

  No - without stock the edges become charged, especially with swimming and higher d.

• Can the angle of ion propagation be ignored?

  No - it determines the M_div. The further away from the web you are, the more length provision you have to add.

• Will mounting oblique to the cylinder axis improve the effect?

  Usually worsens uniformity; maintain parallelism and constant d.

FAQ - quick answers

• Can I order a shorter strip and "make up" for it with blowing?

  Partly yes, but a shorter strip increases the risk of under-ionised edges; it is safer to keep the pattern to L_active.

• Does total length equal active length?

  Usually not - the lugs and power sockets extend the beam beyond the active zone. Always check in the product sheet.

• Can two shorter slats replace one long one?

  Yes - mounted with a light zone cover, they improve service and logistics with wide lines.

Summary

You will quickly calculate the active length of the JO-96 electrode from the principle: L_active = W + 2×(max(20-30 mm, E) + d×tan(θ)), where θ depends on the type of application (smaller without blowing, larger with blowing). Maintain parallelism to the axis of the cylinder, avoid edge shading, and at high speeds and distances consider inflated or two slats in a row. Always confirm whether you are ordering active length or total and leave a reserve for service. A length chosen in this way will ensure an even deionisation of the entire width with no 'dead' edges.