Created on 01.14

Retrofitting IR to Existing Ovens: Layout Options and ROI

Retrofitting infrared (IR) heating into an existing convection oven is rarely about “adding more heat.” The real goal is to reshape the coating’s temperature ramp so you can hit a stable process window: defect-free film formation at your target line speed, without turning the whole oven into a hotter (and more expensive) air heater.

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This guide focuses on three practical outcomes:

Layout options that fit real mechanical constraints (space, airflow, access).
A sizing method you can use before requesting quotes.
An ROI approach that is defensible because it states assumptions, uses measurable inputs, and separates energy savings from throughput benefits.

When an IR retrofit is (and is not) a good idea

A retrofit is usually a good fit when one or more of these are true:

Your line is bottlenecked by warm-up time, changeovers, or slow ramps.
Thick parts or high-mass parts force you to slow speed to avoid under-cure.
You need staged heating (gentle → effective → stabilize) to reduce solvent pop, blistering, or gloss variation.
You have limited floor space and need more heat flux per foot than convection can deliver.

A retrofit is usually a poor fit when:

The main constraint is vapor removal (exhaust/makeup air) rather than heat input.
Quality issues are primarily contamination-related (silicones, oil carryover), not thermal ramp-related.
The coating chemistry requires a long soak at temperature that you cannot shorten (IR can help ramp, but it cannot eliminate chemistry).

What changes when you add IR to a convection oven

Convection heats the air and then relies on air-to-part heat transfer. IR adds direct radiative heat transfer to the coated surface and near-surface layers, which can:

Reduce time-to-temperature (especially for stop/start operations).
Improve ramp control by zoning power where it matters most.
Reduce wasted heating of the oven’s metal mass (particularly in intermittent production).

The key takeaway is that IR retrofits succeed when you use them to control the ramp shape, not just raise peak temperature.

Layout options: four retrofit patterns that cover most ovens

Option 1: “Booster” IR at the entrance (preheat / flash-off assist)

Best for:

Bottlenecks at the front end (slow heat-up, unstable early ramp).
Lines struggling with early-stage defects caused by poor ramp control.

Watch-outs:

If Zone 1 is too aggressive, you can create surface skinning that traps solvent and causes downstream pop.

Option 2: Hybrid IR + convection in the main heating zone

Best for:

Keeping convection for bulk heating while using IR for responsiveness.
Improving stability across mixed part families (different masses) without constantly re-tuning oven temperature.

Evidence you can point to:

An industry test example reported faster heat-up and lower energy use for an IR-convection combination versus convection-only in a batch oven scenario. (See “Data sources” section.)

Option 3: Multi-side IR arrays (top + side, sometimes bottom)

Best for:

Wide belts, complex geometry, edge/corner heating challenges.
Parts where one-sided heating creates uneven cure or appearance variation.

Watch-outs:

Geometry hotspots (edges, ribs) need zoning and/or mechanical shielding.
Clearance and guarding become more critical.

Option 4: Zoned IR modules inside the oven (staged ramp)

Best for:

Solvent-sensitive coatings that need a controlled ramp and stabilization before peak heating.
Plants that run multiple recipes and need repeatability.

Practical staging pattern:

Zone A: gentle pre-warm
Zone B: effective evaporation / drying
Zone C: equalize / stabilize before cure or before entering a downstream cure zone

Sizing method: a practical, defensible approach

You do not need perfect thermal modeling to get 80% of the sizing correct. You need consistent inputs and a simple validation loop.

Step 1: Define your target process window

Write down, in measurable terms:

Target line speed (ft/min or m/min)
Allowed defects (none is not measurable—use pass/fail criteria and inspection points)
Target part temperature profile (what temperature must the coating/part reach, and by when)

If you do not have a temperature profile, you cannot “prove” the retrofit works—only guess.

Step 2: Capture baseline energy and throughput data (2–4 weeks)

Use this table as your baseline checklist.

Data item	Unit	How to collect	Why it matters
Oven energy use	kWh, therms, m³ gas	meter/submeter	ROI numerator
Run hours by recipe	hrs/week	production logs	separates “average” from “real”
Line speed by recipe	ft/min or m/min	PLC / log sheet	defines dwell time
Part mass range	lb or kg	BOM / sample weigh	predicts ramp difficulty
Scrap/rework tied to cure	%	quality logs	monetizes quality gain
Changeover and warm-up time	minutes	operator logs	often the hidden ROI

Step 3: Pick the layout pattern based on your constraint

If you cannot increase length: choose booster IR or high-flux zones.
If you need stability across part families: choose hybrid IR + convection with zoning.
If you have geometry-driven non-uniformity: choose multi-side arrays + zoning.

Step 4: Use a “heat-to-part” test to validate ramp potential

A simple commissioning-style test (even before final hardware) is often more valuable than assumptions:

Measure part surface temperature rise vs time at a known distance/power setting.
Record ramp rate and uniformity across the belt width.
Identify hotspots early (edges, corners, thin sections).

This becomes your engineering evidence, and it reduces retrofit risk materially.

ROI: build it from measurable blocks (not generic percentages)

ROI components you should separate

Energy savings
Demand savings(if you pay demand charges)
Throughput gains(faster speed, fewer bottlenecks)
Quality gains(less scrap/rework, fewer defects)
Maintenance deltas(parts, downtime, cleaning)

Core formulas (simple payback and annual benefit)

Annual energy cost = (electric kWh × $/kWh) + (gas × $/unit)
Annual net savings = (baseline cost − new cost) − added maintenance + avoided downtime value
Simple payback (years) = retrofit CAPEX / annual net savings

Worked example (illustrative, replace with your numbers)

Assumptions (state yours explicitly):

Baseline oven energy cost: $120,000/year
Retrofit changes:

Net energy reduction: 18% (after accounting for any added electric load)
Reduced warm-up/changeover time value: $10,000/year
Maintenance increase: $2,000/year

Retrofit CAPEX installed: $140,000

Calculation:

Energy savings = $120,000 × 0.18 = $21,600/year
Annual net savings = $21,600 + $10,000 − $2,000 = $29,600/year
Simple payback = $140,000 / $29,600 = 4.73 years

Sensitivity table (why ROI varies so much)

Net energy reduction	Annual net savings (example)	Simple payback (CAPEX $140k)
10%	~$20,000/year	~7.0 years
20%	~$32,000/year	~4.4 years
30%	~$44,000/year	~3.2 years

The point is not the exact number. The point is that ROI is dominated by (a) verified net energy change and (b) whether you monetize warm-up/changeover and throughput, which are often larger than the pure “fuel saved” story.

What counts as “empirical” proof for a retrofit project

If you want the retrofit to hold up under management review (and not be dismissed as marketing), build a minimal measurement plan:

A practical M&V plan aligned with ISO 50001 thinking

Define an Energy Performance Indicator (EnPI): e.g., kWh per coated part, or energy per square foot of coated area.
Define an Energy Baseline (EnB): baseline EnPI for a stable period (same product mix if possible).
Measure post-retrofit EnPI and normalize for meaningful drivers: line speed, part mass, product mix.

This approach is consistent with how ISO 50001 frames energy performance improvement (process + measurement discipline). It also prevents arguments like “savings happened because we ran fewer heavy parts.”

Safety and compliance checkpoints (do not skip these)

Even if your retrofit is “inside the existing oven,” it can change hazard profiles:

Solvent and vapor management: confirm exhaust and makeup air remain adequate.
Surface temperatures and ignition risks: staged ramp matters.
Interlocks and guarding: access doors, maintenance mode, and emergency stops must remain effective.
Applicable oven safety standards and internal EHS rules should be reviewed during design, not after installation.

Also note that coatings test methods (e.g., drying/curing standards) explicitly remind users that standards do not address all safety concerns; the user is responsible for establishing appropriate practices.

Commissioning checklist (fast, low-risk)

Set a conservative heater-to-part distance that tolerates part height variation.
Build staged recipes; do not peak power in Zone 1.
Validate belt-width uniformity (edge vs center).
Increase speed in steps; document stable recipes per part family.
Record EnPI before/after and normalize by product mix.
Lock in inspection checkpoints (appearance + cure metrics).

FAQ

1) Can I retrofit IR without changing airflow?

Sometimes, but not always. If your constraint is vapor removal (solvent-laden air), IR alone may not solve defects. Heat and ventilation have to work together.

2) Will IR always reduce energy use?

No. It often reduces energy when it shortens cycle time, reduces warm-up losses, or enables zoning. If the retrofit adds significant electrical load without reducing run time, net savings may be smaller.

3) Is “booster IR” enough for most retrofits?

For many lines, yes—especially when the main pain is early ramp control or warm-up. If your bottleneck is bulk heating or soak time, you may need hybrid or multi-zone layouts.

4) How do I avoid solvent pop after retrofitting?

Prioritize ramp shape: gentle early heating, staged zones, and adequate vapor management. Many “downstream” defects start with an overly aggressive first zone.

5) What data should I bring to a retrofit discussion?

Line speed targets, part mass range, coating type and thickness range, defect history, available length/clearance, and baseline energy use by operating mode.

6) What’s the most credible way to claim ROI?

Use a measured baseline, define EnPI/EnB, state assumptions, and show calculations. Avoid generic percent claims without boundaries.

CTA

If you are considering an IR retrofit, prepare a one-page retrofit brief before requesting quotes:

product families and line speeds
coating type + thickness range
defect history
available installation length and clearance
2–4 weeks of baseline energy + throughput logs

This single page typically reduces retrofit risk more than any single hardware decision.

Data sources (non-competitor, standards/academic/agency)

ASTM D1640/D1640M (Drying/Curing/Film Formation test methods; scope and safety notes).
ISO 50001:2018 (Energy management systems; EnPI/EnB framework and performance monitoring concepts).
U.S. DOE / NREL BestPractices case study (reported 25% natural gas reduction and 2.5-year simple payback after adding an IR curing oven, plus annual savings).
Industry technical article with measured comparison (IR-convection vs convection-only: ~37% faster heat-up and ~26% energy reduction in an example test).

Last modified: 2026-01-15

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