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In-Mold Labeling (IML)

Marking & decoration · Printing

In-mold labeling places a preprinted label in the mold before plastic is injected.

Injection moldingPremium cost $$$Unchanged
Quote a part with IMLCompare marking & decoration
In-Mold Labeling (IML) on a machined part

What is IML?

The label bonds into the part surface and is used for durable product graphics, instructions, barcodes, and regulatory information.

How it works

A printed and die-cut polymer label is picked, oriented, and held against the cavity by static charge, vacuum, or mechanical location. Molten resin fills behind it and heat and pressure bond the label to the molded part. The label becomes the visible surface rather than a post-applied decal. Label stock, ink, resin, mold venting, and gate position must be compatible to prevent wrinkles, trapped air, distortion, and edge lift. ASTM F2252 is a tape-adhesion practice for ink or coating on flexible packaging, not a general ink-abrasion test; use it only when the label construction is within its scope.

Why specify it

  • Integrates label application with molding
  • Supports full-colour graphics and machine-readable codes
  • Uses a typical 50–150 µm label stock
  • Resists edge picking better than many pressure-sensitive labels

Where it falls short

  • Requires automated label handling and mold development
  • Artwork can distort from shrinkage and flow
  • Trapped air causes blisters or incomplete bonding
  • Artwork revisions require new printed label inventory

IML at a glance

IML is strongest on cosmetic quality (88 of 100), at a premium cost. It adds little lubricity. Corrosion protection and surface hardness are not rated: a plastic part does not corrode, and the finish leaves the part's own surface.

Corrosion protectionNot rated—
Surface hardnessNot rated—
Cosmetic qualityExcellent88 / 100
LubricityMinimal10 / 100
Relative costPremium48 / 100
CorrosionHardnessCosmeticLubricityEconomy

Each score is 0–100 against every finish in this catalog. Corrosion comes from salt-spray life (ASTM B117, log scale) and hardness from the finish layer's Vickers or pencil hardness; cosmetic, lubricity and cost are FabDigit's engineering assessment. Economy on the radar is the inverse of cost.

IML key numbers

Typical values from the governing specifications and shop practice; bars are this finish against the highest value among marking & decoration finishes.

Thickness50–150 µm2–5.9 mil
Thickness
50–150 µm label stock inherited from v1; printed ink is only part of this stack.
Electrical
Unchanged
Colours
  • full colour
  • white
  • transparent
  • metallic effects
Appearance
Label-quality gloss, matte, photographic, or transparent artwork integrated into the molded surface.

Specifications for IML

The documents a drawing cites to define this finish, with the Type / Class rows that apply. Each links to a page explaining the standard.

Test and related methods: ASTM F2252 (Standard Practice for Evaluating Ink or Coating Adhesion to Flexible Packaging Materials Using Tape), ISO 15415 (Automatic Identification and Data Capture Techniques — Bar Code Symbol Print Quality Test Specification — Two-Dimensional Symbols), ISO 15416 (Automatic Identification and Data Capture Techniques — Bar Code Symbol Print Quality Test Specification — Linear Symbols).

Drawing call-out

IN-MOLD LABEL PER ARTWORK IML-308 REV D, 75 µm PP LABEL, MATTE, REGISTRATION ±0.50 MM; DATA MATRIX GRADE 2.5 MIN PER ISO 15415

Which materials take IML?

Verdict per material family, with the grades that behave differently. Each family links to its datasheets in the material library.

Material familyVerdictNotes
Polymer
YesCommon with resin-compatible labels in injection molding.
  • Match label stock to resin family and molding temperature
Aluminum
NoIML is an injection-mould polymer process.
Brass
NoIML is an injection-mould polymer process.
Copper Alloy
NoIML is an injection-mould polymer process.
Magnesium Alloy
NoIML is an injection-mould polymer process.
Stainless Steel
NoIML is an injection-mould polymer process.
Steel
NoIML is an injection-mould polymer process.
Titanium
NoIML is an injection-mould polymer process.
Zinc Alloy
NoIML is an injection-mould polymer process.

How IML is applied, and what it does to the part

  1. 1Print label
  2. 2Die-cut label
  3. 3Load and register in mold
  4. 4Hold label against cavity
  5. 5Injection mold part
  6. 6Eject and inspect bond and registration
DimensionsInclude the 50–150 µm label stock in cavity and wall-thickness review.
Build-up per side50–150 µm — The label occupies part of the molded wall and visible surface.
MaskingRarely needed. Keep the label clear of gates, vents, sealing faces, weld interfaces, and assembly bonds.
ElectricalUnchanged
AppearanceLabel-quality gloss, matte, photographic, or transparent artwork integrated into the molded surface.
Added lead time10–20 working days on top of the bare part

Design rules for IML

What to decide on the drawing before the part goes to the finisher.

  1. Keep critical text and codes away from label edges and high-draw regions.Shrinkage and flow can distort print.
  2. Provide a draft-free, smooth label seating zone.The label must lie against the cavity without wrinkling.
  3. Keep gates and vents out of the visible label field.Flow and gas can lift or blister the insert.
  4. Grade production barcodes on the molded geometry.Curvature, gloss, and distortion affect scanner performance.

IML versus the alternatives

Finishes engineers weigh against IML, and when each wins.

FinishCorrosionHardnessCosmeticCostThicknessChoose it when
IML
this page
——88$$$50–150 µm—
In-Mold Decoration (IMD)
IML vs In-Mold Decoration (IMD) →
——92$$$$100–300 µmfor formed decorative-film interfaces
Screen Printing
IML vs Screen Printing →
0—75$10–25 µmfor lower-volume flat graphics
CorrosionHardnessCosmeticLubricityEconomy
IMLIn-Mold Decoration (IMD)

The radar overlays IML with In-Mold Decoration (IMD), its most common alternative — chosen for formed decorative-film interfaces. Scores in the table are 0–100 across every finish in the catalog.

Cost, lead time and compliance

Relative cost

In-Mold Labeling (IML) is a premium-cost finish ($$$): more expensive than about 55 % of the finishes FabDigit quotes.

Finishing is priced per part with a lot minimum, from FabDigit's own China-side rates. The exact figure appears on the instant quote once the part is uploaded.

Lead time and compliance

Added lead time10–20 working days
RoHSCompliant
NotesUsing label stock compatible with the molded resin can improve recyclability; inks and coatings still require declarations.

What IML is used for

  • Food containers
  • Detergent packaging
  • Durable instruction labels
  • Rugged handheld housings
  • Regulatory and traceability labels

IML — frequently asked

What is the difference between IML and IMD?

IML generally uses a die-cut printed label that bonds into a molded container or part. IMD often uses a larger decorative film that may be thermoformed for an interface or trim surface.

How thick is an in-mold label?

This catalog carries the v1 range of 50–150 µm for label stock. State the actual material and nominal thickness on the approved label specification.

Can an IML barcode be graded after molding?

Yes; grade 2D symbols with ISO 15415 and linear symbols with ISO 15416 on the finished part. Curvature, gloss, flow distortion, and label registration can reduce the grade compared with the flat printed label.

Does IML peel off?

A compatible label bonds into the molded surface and normally resists edge picking better than a post-applied decal. Poor resin compatibility, contamination, trapped air, or low bonding temperature can still cause edge lift.

Can IML be used on curved surfaces?

Yes, especially on containers with developable walls, but the label and artwork must tolerate mold curvature and shrinkage. Deep compound geometry needs placement trials and compensated artwork.