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Injection molding drawing notes

By Fred Vierheller, senior mechanical engineer, Certified SOLIDWORKS Professional · Updated November 4, 2026

18 copy-ready notes for plastic injection molding, in English and Spanish. Copy a note, replace the [bracketed] example values, and check the "Watch for" line before you release the drawing.

Values in [brackets] are examples; replace them with your own. Notes marked Verify values rely on common practice; confirm them with your supplier or design engineer. These notes are examples, not an engineering approval of your drawing.

INJ-01 ResinINJ-02 DraftINJ-03 Draft directionINJ-04 Wall and rib thicknessINJ-05 FilletsINJ-06 Flash, parting line, gate and ejector marksINJ-07 Cosmetic requirementsINJ-08 Surface finish and textureINJ-09 Conditioning before measuringINJ-10 Molded-in markingINJ-11 Steel-safe featuresINJ-12 Plastic tolerances (metric)MLD-01 Tool design approvalMLD-02 Mold flowMLD-03 Mold steelMLD-04 Automatic moldingMLD-05 CoolingMLD-06 Mold standards

Part notes

INJ-01

Resin

Verify values
EN
MATERIAL: [POLYCARBONATE, SABIC LEXAN 940], COLOR [BLACK, MATCH CHIP ___]. REGRIND [NOT PERMITTED / 10% MAX].
ES
MATERIAL: [POLICARBONATO, SABIC LEXAN 940], COLOR [NEGRO, IGUALAR MUESTRA ___]. MOLIDO [NO PERMITIDO / 10% MÁX.].

Use: every molded part: resin family, maker, grade, color and regrind limit.

Watch for: "ABS" or "NYLON" alone; the recycling triangle number used as the material spec (that's ASTM D7611 marking, not a spec); "OR EQUIVALENT" with no approver.

Basis: convention. verify (grade is an example)

INJ-02

Draft

Verify values
EN
DRAFT [1]° MIN PER SIDE UNLESS NOTED. TEXTURED SURFACES: ADD [1.5]° PER [.001] OF TEXTURE DEPTH.
ES
ÁNGULO DE SALIDA [1]° MÍN. POR LADO A MENOS QUE SE INDIQUE. SUPERFICIES TEXTURIZADAS: AGREGAR [1.5]° POR CADA [.001] DE PROFUNDIDAD DE TEXTURA.

Use: every molded part.

Watch for: "MINIMUM DRAFT REQUIRED" — no value; draft not stated as added to or taken from the nominal size.

Basis: Protolabs design guide (0.5° minimum, 1–2° typical); texture rule of thumb from texture suppliers. verify

INJ-03

Draft direction

Verify values
EN
(+) INDICATES DIMENSION PLUS DRAFT. (–) INDICATES DIMENSION MINUS DRAFT.
ES
(+) INDICA DIMENSIÓN MÁS SALIDA. (–) INDICA DIMENSIÓN MENOS SALIDA.

Use: when the drawing gives sizes at one end of a drafted wall.

Basis: convention. verify

INJ-04

Wall and rib thickness

Verify values
EN
NOMINAL WALL [.080]. RIBS [50–60]% OF ADJOINING WALL UNLESS NOTED.
ES
PARED NOMINAL [.080]. COSTILLAS [50–60]% DE LA PARED ADYACENTE A MENOS QUE SE INDIQUE.

Use: parts where the model is the authority for detail geometry.

Watch for: ribs as thick as the wall (sink marks on the other side).

Basis: Protolabs and resin supplier design guides. verify

INJ-05

Fillets

Verify values
EN
INSIDE FILLETS R[.020], OUTSIDE R[.020] + WALL, UNLESS NOTED.
ES
RADIOS INTERIORES R[.020], EXTERIORES R[.020] + PARED, A MENOS QUE SE INDIQUE.

Basis: convention. verify

INJ-06

Flash, parting line, gate and ejector marks

Verify values
EN
FLASH [.005] MAX. PARTING LINE MISMATCH [.003] MAX. GATE VESTIGE [.010] MAX ABOVE SURFACE. EJECTOR MARKS FLUSH TO [.005] BELOW SURFACE.
ES
REBABA [.005] MÁX. DESALINEACIÓN EN LÍNEA DE PARTICIÓN [.003] MÁX. VESTIGIO DE COMPUERTA [.010] MÁX. SOBRE LA SUPERFICIE. MARCAS DE BOTADOR AL RAS HASTA [.005] BAJO LA SUPERFICIE.

Use: every molded part; mark parting line, gate and ejector areas on the drawing.

Watch for: limits tighter than the molder can hold (.002 flash on a commodity part) without a reason.

Basis: convention; confirm with the molder. verify

INJ-07

Cosmetic requirements

Verify values
EN
SURFACES MARKED [△20] ARE CLASS A: NO SINK, FLOW LINES, KNIT LINES, SPLAY OR GATE BLUSH VISIBLE AT [18] IN UNDER [STANDARD LIGHTING]. ACCEPTANCE BY APPROVED LIMIT SAMPLES.
ES
LAS SUPERFICIES MARCADAS [△20] SON CLASE A: SIN RECHUPES, LÍNEAS DE FLUJO, LÍNEAS DE UNIÓN, SALPICADO NI MANCHA DE COMPUERTA VISIBLES A [18] PULG. ACEPTACIÓN CONTRA MUESTRAS LÍMITE APROBADAS.

Use: visible consumer and automotive parts.

Watch for: "NO SINK MARKS PERMITTED" everywhere — impossible on thick bosses; limit it to cosmetic faces.

Basis: convention; Plastics Industry Association cosmetic guidance (current edition: verify).

INJ-08

Surface finish and texture

Verify values
EN
MOLD FINISH: SPI [B-2] UNLESS NOTED. SURFACES MARKED [△21]: TEXTURE [MT-11010] (OR VDI 3400 [REF 27]).
ES
ACABADO DEL MOLDE: SPI [B-2] A MENOS QUE SE INDIQUE. SUPERFICIES MARCADAS [△21]: TEXTURA [MT-11010] (O VDI 3400 [REF 27]).

Use: every molded part. SPI grades A-1 (mirror) to D-3 (coarse blast).

Watch for: "DME A-1" naming (it's the SPI scale); texture with no added draft (INJ-02).

Basis: SPI finish grades still the industry name (association now the Plastics Industry Association); VDI 3400. checked. Texture number is an example. verify

INJ-09

Conditioning before measuring

Checked
EN
DIMENSIONS APPLY AFTER CONDITIONING PER ASTM D618, [40] H AT 23 °C / 50% RH.
ES
LAS DIMENSIONES APLICAN DESPUÉS DE ACONDICIONAR SEGÚN ASTM D618, [40] H A 23 °C / 50% HR.

Use: every molded part, especially nylon (absorbs moisture).

Watch for: "3 DAYS AFTER MOLDING" with no temperature or humidity.

Basis: ASTM D618 Procedure A (40 h for ≤7 mm thick). checked (secondary source; check current text)

INJ-10

Molded-in marking

Checked
EN
MOLD IN: PART NUMBER, CAVITY NUMBER, DATE WHEEL, MATERIAL ID PER ISO 11469 (E.G. >PC<) AT LOCATION [△22], [.010] RAISED.
ES
MOLDEAR: NÚMERO DE PARTE, NÚMERO DE CAVIDAD, FECHADOR E IDENTIFICACIÓN DE MATERIAL SEGÚN ISO 11469 (EJ. >PC<) EN [△22], [.010] EN RELIEVE.

Use: production molds. Put the revision on a changeable insert, not an ejector pin.

Basis: ISO 11469 (plastics marking). checked

INJ-11

Steel-safe features

Verify values
EN
[S] INDICATES STEEL-SAFE DIMENSION: CUT TOOL TO [MAX MATERIAL] FOR LATER TUNING.
ES
[S] INDICA DIMENSIÓN DE ACERO SEGURO: MAQUINAR EL MOLDE A [MÁXIMO MATERIAL] PARA AJUSTE POSTERIOR.

Use: snap fits, bosses and mating features that will be tuned after first shots.

Basis: convention. verify

INJ-12

Plastic tolerances (metric)

Verify values
EN
GENERAL TOLERANCES: ISO 20457, [TG6].
ES
TOLERANCIAS GENERALES: ISO 20457, [TG6].

Use: metric molded parts; replaces old DIN 16901 callouts.

Basis: ISO 20457 (a 2026 edition replaced 2018). checked. Grade is an example. verify

Mold build requirements (tooling notes)

MLD-01

Tool design approval

Verify values
EN
MOLD DESIGN, PARTING LINE, GATE, VENT AND EJECTOR LOCATIONS TO BE APPROVED BY [CUSTOMER] BEFORE STEEL IS CUT.
ES
EL DISEÑO DEL MOLDE, LÍNEA DE PARTICIÓN, COMPUERTAS, VENTILAS Y BOTADORES DEBEN SER APROBADOS POR [CLIENTE] ANTES DE CORTAR ACERO.
MLD-02

Mold flow

Verify values
EN
MOLD FLOW ANALYSIS REQUIRED, USING THE SPECIFIED RESIN GRADE (NOT A GENERIC MATERIAL).
ES
SE REQUIERE ANÁLISIS DE LLENADO CON EL GRADO DE RESINA ESPECIFICADO (NO UN MATERIAL GENÉRICO).
MLD-03

Mold steel

Verify values
EN
CORE AND CAVITY: [PREMIUM H13], [48–52] HRC. SLIDES AND LIFTERS: [H13].
ES
CORAZÓN Y CAVIDAD: [H13 PREMIUM], [48–52] HRC. CORREDERAS Y LEVANTADORES: [H13].
MLD-04

Automatic molding

Verify values
EN
MOLD SHALL RUN FULLY AUTOMATIC: SUB OR HOT-DROP GATES, GUIDED EJECTION, SLIDE RETAINERS.
ES
EL MOLDE DEBE OPERAR EN AUTOMÁTICO: COMPUERTAS SUBMARINAS O DE CÁMARA CALIENTE, EXPULSIÓN GUIADA, RETENES EN CORREDERAS.
MLD-05

Cooling

Verify values
EN
ALL INSERTS AND SLIDES COOLED. WATER LINES WITH QUICK DISCONNECTS, LABELED IN/OUT.
ES
TODOS LOS INSERTOS Y CORREDERAS CON ENFRIAMIENTO. LÍNEAS DE AGUA CON CONEXIONES RÁPIDAS, ROTULADAS ENTRADA/SALIDA.
MLD-06

Mold standards

Verify values
EN
CLAMP SLOTS, LOCATING RING [Ø3.990] AND SPRUE PER [CUSTOMER PRESS STANDARD].
ES
RANURAS DE SUJECIÓN, ANILLO CENTRADOR [Ø3.990] Y BEBEDERO SEGÚN [ESTÁNDAR DE PRENSAS DEL CLIENTE].

Basis: convention from Fred's mold standard. verify

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