SikaFast®-321 S

Fast curing, 2-component toughened structural adhesive with shims

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SikaFast®-321 S is an acrylic based, fast curing, flexibilized structural, 2-component adhesive with incorporated spacer shims (0.027 ─ 0.033 inch / 0.68 ─ 0.84 mm) to maintain uniform bond thickness. SikaFast®-321 S is for use in applications requiring quick fixturing for higher throughput. It is designed to efficiently transfer high loads and evenly distribute stresses. SikaFast®-321 S provides very good adhesion on various substrates and is suitable to replace mechanical fixation.

Strength development within minutes after application
Superior low-temperature flexibility compared to other structural adhesives
Spacer for control of bond thickness
Adhesion to a wide range of substrates without or with limited surface preparation
High elongation and ductility
Good strength and impact resistance

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Product Data Sheet Show all documents

PRODUCT BENEFITS

Strength development within minutes after application
Superior low-temperature flexibility compared to other structural adhesives
Spacer for control of bond thickness
Adhesion to a wide range of substrates without or with limited surface preparation
High elongation and ductility
Good strength and impact resistance

Usage

SikaFast®-321 S is designed for fast bonding and can replace or complement mechanical fixations such as rivets, screws or welding. It is suitable for high strength fastening of concealed joints and exhibits very good adhesion on different types of substrates including aluminum, stainless or galvanized steel and fiber reinforced polymers. This product is suitable for experienced professional users only. Tests with actual substrates and conditions have to be performed ensuring adhesion and material compatibility.

Packaging

Dual cartridge

490 ml

Product Details

Typical Product Data

Properties

SikaFast®-321 S (A)

SikaFast®-3081 N (B)

Chemical base

Methacrylate

Color (CQP001-1)

mixed

Natural	White
Straw

Cure mechanism

Radical polymerization

Density

mixed (calculated)

0.96 kg/l (8.0 lb/gal)	1.30 kg/l (10.8 lb/gal)
0.99 kg/l (8.3 lb/gal)

Mixing ratio

by volume

by weight

10 : 1

7.4 : 1

Consistency

Thixotropic paste

Application temperature

10 ─ 35 °C (50 ─ 95 °F)

Open time (CQP526-2)

5 minutes ^A

Peak exotherm time / temperature

10 minutes / 90 °C (194 °F) ^A

Shore D hardness (CQP023-1 / ISO 48-4)

Tensile strength (ASTM D638)

9 MPa (1300 psi)

Elongation at break (ASTM D638)

80 %

E-Modulus (ASTM D638)

elongation 0 ─ 5 %

100 MPa (14 500 psi)

Tensile lap-shear strength (CQP046-6 / ISO 4587)

10.5 MPa (1500 psi)

Service temperature (CQP513-1)

-30 ─ 80 °C (-22 ─ 176 °F)

Shelf life

9 months ^B

CQP = Corporate Quality Procedure	^A) 23 °C (73 °F) / 50 % r. h.
	^B) Stored at temperature below 22 °C (72 °F) protect from direct sun light

Technical Information

CURE MECHANISM

SikaFast®-321 S cures according to radical chain polymerization. For an ideal curing process, it is required to homogeneously mix both components with the defined ratio. Open and cure time are influenced by mixing ratio deviations as well as temperature, e.g., the higher the temperature the shorter the open and cure time and vice versa.
Despite the quick strength build-up, exposure to premature stresses must be avoided since this may result in a reduction of mechanical properties and loss of adhesion.

CHEMICAL RESISTANCE

In the view of potential chemical or thermal exposure, it is required to conduct project related testing.

Application

Application Information

Surface Preparation

Surfaces must be clean, dry and free from grease, oil and dust. Remove all loose particles or residues by cleaning it thoroughly, for example with an IPA wipe.
Due to the diversity of materials, preliminary tests with original substrates are necessary.

Application

SikaFast®-321 S is applied with a mixing ratio of 10:1 by volume through an 18-element static mixer. If applied in large masses, heat is generated by the exothermic reaction. To avoid excessive temperature increase, bond thickness is limited to 5 mm (0.197 in), but must measure at least 0.5 mm (0.020 in).

Optimum temperature for the bonding process is between 15 °C and 25 °C (59 °F and 77 °F). The approved temperature range for substrates and adhesive is between 10 °C and 35 °C (50 °F and 95 °F). The influence of the reactivity by temperature changes has to be respected.

The parts must always be joined within the open time. For support in evaluation of the appropriate application equipment contact the System Engineering department of Sika Industry.

Removal

Uncured excess of SikaFast®-321 S can be removed easily before curing with a dry wipe, with Sika® Remover-208 or another suitable solvent. Once the adhesive is cured it can only be removed mechanically.
Hands and exposed skin should be washed immediately using a suitable industrial hand cleaner and water.

Do not use solvents on skin.