Created on 01.09
IR Dryer Setup: Distance, Power, and Line Speed
If your IR paint drying line shows uneven gloss, edge overheating, solvent pop, or inconsistent cure, the root cause is often not “the heater” but the relationship between three variables:
- Distance (heater-to-part gap)
- Power (how much energy you deliver)
- Line speed (how long the part is exposed)
These variables control heat flux and dwell time—and together they determine the coating’s temperature ramp and evaporation behavior. This guide gives a practical way to set up and tune an IR dryer for stable paint drying without guesswork.Infrared Paint Drying Pillar
The tuning mindset: control heat flux and exposure time
IR drying is not just “more power = more drying.” Paint defects often happen when you push one variable without balancing the others.
- Distance mainly changes how intense the radiant energy is at the surface (heat flux).
- Power changes total energy available and how fast temperature rises.
- Line speed changes dwell time, which multiplies everything (total energy delivered).
A stable process usually needs:
- a controlled ramp (especially early)
- adequate flash-off/stabilization
- good uniformity across part geometry and line width
Start with the end goal: what “good” looks like
Before adjusting anything, define your target condition:
- defect-free surface (no pop, pinholes, blisters)
- consistent appearance (gloss/leveling)
- stable drying/cure downstream (repeatable across shifts)
- throughput target (line speed) with acceptable energy use
If you can’t measure quality consistently, tuning becomes random.
Understand each variable (what it changes and what it breaks)
1) Distance (heater-to-part gap)
What it controls
- surface heating intensity
- risk of hotspots on edges/corners
- sensitivity to part height variation
What goes wrong when distance is too small
- surface skinning → trapped solvent → solvent pop
- edge overheating and gloss variation
- small geometry differences create big temperature differences
What goes wrong when distance is too large
- slow response, insufficient drying at higher speed
- loss of controllability (you compensate with power and create instability)
Practical advice
- distance should be stable and repeatable (fixtures matter)
- keep clearance that tolerates part variation without accidental overheating
2) Power (total IR output / zone power)
What it controls
- ramp rate (how fast temperature rises)
- ability to compensate for speed changes
- total energy available for evaporation and curing stages
What goes wrong when power is too high (especially early zones)
- fast surface heating → skinning → defects later
- uneven appearance due to overheating peaks
- “looks fine after flash-off, fails later in the oven”
What goes wrong when power is too low
- incomplete flash-off, unstable downstream cure
- operator keeps increasing speed and quality collapses
Practical advice
- use staged power (gentle → moderate → stabilize)
- avoid big jumps between zones
3) Line speed (exposure time)
What it controls
- dwell time under each zone
- total energy delivered (energy = flux × time)
- throughput vs stability trade-off
What goes wrong when speed increases without recipe updates
- under-drying in early stages
- downstream defects due to insufficient flash-off
- inconsistent results across batches
Practical advice
- every speed change should be paired with a defined recipe change (power by zone and sometimes distance/airflow)
The most common tuning mistake: changing two things at once
To tune fast and safely:
- change one variable per test
- record settings and outcomes
- allow enough time for the line to stabilize before judging results
A simple rule:
- Adjust distance first for safe flux
- Then tune zone power for ramp shape
- Then increase line speed gradually
A practical setup sequence (recommended workflow)
Step 1: Establish a conservative baseline
Start with:
- a safe distance (not too close)
- low-to-moderate early-zone power
- moderate line speed (not your maximum)
Your goal is a stable, defect-free baseline.
Step 2: Build a staged heating profile
A stable IR paint drying profile typically includes:
- Zone 1 (pre-warm / gentle flash-off start): avoid early peaks
- Zone 2 (evaporation / drying): steady solvent release
- Zone 3 (stabilization / equalization): prepare for cure stage
If your dryer has more zones, keep the same idea: early gentle, mid effective, late stable.IR Flash-Off vs Convection
Step 3: Tune distance for uniformity and safety
Distance is your “risk control” lever. Set it so you avoid:
- edge burn / corner hotspots
- sensitivity to part height variation
- skinning in the first zone
Once distance is safe and repeatable, lock it.
Step 4: Tune power by zone (shape the ramp)
Adjust power to achieve:
- smooth ramp-up without early spikes
- enough mid-zone energy for consistent drying
- stable transition into downstream cure
Step 5: Increase line speed in small increments
Increase speed step-by-step and compensate with zone power (and sometimes airflow/ventilation). Watch defect trends:
- if defects appear after increasing speed, your flash-off may be insufficient
- if defects appear immediately after IR zone, you may be too aggressive early
Zoning and geometry: the key to uniformity
Even perfect distance/power/speed can fail if heating is uneven.
When zoning matters most
- wide parts or wide conveyor widths
- parts with edges, corners, ribs, or cutouts
- mixed part families on one line
Common zoning strategy
- reduce edge zones slightly if edges overheat
- increase center zones if center stays wet
- compensate for shadows or occlusions by adding zones or repositioning emitters
Zoning is often the easiest way to fix “looks fine in the middle, bad on the edges.”
Measurement: how to verify you’re tuning correctly
Track surface temperature (not just power settings)
Power settings do not guarantee the same heating result across:
- different coatings
- different substrates
- different ambient conditions
Use consistent checks:
- monitor surface temperature in repeatable locations
- validate after any change (speed, coating, part geometry)
Watch the “defect timing”
- defects right after IR zone → early flux too high / distance too small / Zone 1 too aggressive
- defects later in oven → flash-off insufficient / vapor removal weak / ramp too steep mid-stage
Troubleshooting map (fast diagnosis)
Problem: solvent pop / blistering
Likely causes:
- too much early power
- distance too small
- insufficient flash-off time
Fix sequence:
- reduce Zone 1 power (or increase distance slightly)
- add staged ramp
- improve vapor removal / air exchange
Problem: uneven gloss / leveling issues
Likely causes:
- uneven heating across width/geometry
- film setting too quickly
Fix sequence:
- improve zoning
- reduce early ramp aggressiveness
- stabilize airflow patterns if used
Problem: center wet, edges dry (or reverse)
Likely causes:
- zone imbalance
- distance variation across width
Fix sequence:
- rebalance zones
- verify mechanical alignment and consistent distance
Problem: stable at low speed, fails at high speed
Likely causes:
- dwell time too short without recipe changes
Fix sequence:
- create a high-speed recipe (zone powers)
- verify flash-off remains adequate
- avoid solving speed issues with a single early-zone power increase
Commissioning checklist (copy/paste for your SOP)
- Confirm wet film thickness is consistent
- Lock a safe heater distance that tolerates part height variation
- Create staged zone profile (gentle → effective → stabilize)
- Validate uniformity (edges vs center; complex features)
- Define recipes for at least 2–3 line speeds
- Record zone powers, distance, speed, and any airflow/exhaust settings
- Re-validate after coating/substrate changes
FAQ
1) Which should I change first: distance, power, or speed?
Start with distance to ensure safe, uniform flux. Then shape the ramp with zone power. Increase speed last, in small steps.
2) Why does raising power sometimes increase defects instead of drying faster?
Because high early flux can create surface skinning and trap solvent. The part may look fine initially but defect later in the oven or after cooling.
3) Can I tune using only power settings without temperature checks?
You can try, but repeatability is weaker. Temperature checks help you confirm the ramp and spot drift across shifts, coatings, or substrates.
4) How do I handle mixed parts on the same line?
Use zoning and recipes. If geometry varies significantly, define separate settings (or a “safe” universal recipe) and verify edge/corner behavior.
5) What inputs are needed to recommend an IR dryer setup?
Coating type and wet film thickness, substrate, part dimensions/geometry, target line speed, target temperature/cure requirement, and installation constraints.
Last modified: 2026-01-09
Home
About Us
Products
Replacement IR Lamps
Project
News
Contact Us
Home
About Us
Products
Replacement IR Lamps
Project
News
Contact Us
Copyright © 2025 Huai'an Infrared Heating Technology. All Rights Reserved.
Address: No 148, huaihai east road, huai'an city, jiangsu, china
Phone / WhatsApp: +86-13852327847
Contact : Ryan Chou
Email: info@yinfrared.com
Product List
Product List
Subscribe
Subscribe
For inquiries about our products or pricelist, please leave to us and we will be in touch within 24 hours.
Quick Links
Quick Links
medium wave ir lamp
short wave ir heater
power control
carbon ir heater
uv lamps
replacement ir lamps
medium wave ir lamp
short wave ir heater
power control
carbon ir heater
uv lamps
replacement ir lamps