Closed assembly time

However, good penetration into the wood is a very important aspect of wood bonding. Standards such as ASTM D 2559 require bond formation within the minimum and maximum of the recommended open and closed assembly times [9], Sufficient penetration into the wood is considered important for good bond formation, but overpenetration produces a starved bondline that is the weak link. Overpenetration does not occur with non-porous substrates thus, different factors need to be considered in formulating and using wood adhesives. A lower viscosity adhesive is normally better for the wetting and adhesion, but for wood the adhesive can be so thin as to overpenetrate into the wood. 

For phenolic FRP-wood bonded assemblies, the following factors relating to the performance of the bonded interface were investigated (1) the influence of coupling agents, (2) the influence of clamping pressure, and (3) the influence of open/closed assembly time. The sizes of the specimens used were smaller than those specified in ASTM D2559. Each laminated FRP-wood assembly for the delamination test consisted of four pieces of red maple wood and two pieces of FRP strips four wood pieces [each 19.05 mm X 76.2 mm X 609.6 mm (0.75" x 3" x 24")] were placed at the center of the... 

Pressurep=l.448MPa (210 psi) open/closed assembly time t = 3/50 min. ... 

Bonded assemblies composed of 6 lamellae are prepared from straight-grained spruce with a density of (425 25) kg/m at(12 l)% moisture content. They must be bonded with the shortest and the longest closed assembly times given in the technical data sheet of the product to be tested. The open assembly time is set to be shorter than 5 min and the pressure applied for bonding is set to 0.6 N/mm. ... 

Time, assembly n. The time interval between the spreading of the adhesive on the adher-end and the application of pressure or heat, or both, to the assembly. Note—For assemblies involving multiple layers or parts, the assembly time begins with the spreading of the adhesive on the first adherend. (1) Open assembly time is the time interval between the spreading of the adhesive on the adherend and the completion of assembly of the parts for bonding. (2) Closed assembly time is the time interval between... 

Note 2 A caul may be made of any suitable material such as aluminum, stainless steel, hardboard, fiberboard, or plastic the length and width dimensions being generally the same as those of the platen of the press where it is used, cement, n See adhesive, cement, v See bond, v. closed assembly time See time, assembly. 

Woo (1982, personal communication) has described the exterior plywood adhesive formulation based on Tannaphen and used commercially by New Zealand Forest Products Ltd. since 1981 as Tannaphen - 56 parts, a phenol-formaldehyde fortifying resin - 21 parts, olivestone flour - 18 parts, and paraformaldehyde - 5 parts on weight of solids. These adhesives are tolerant of open assembly times of 20 minutes, closed assembly times of up to 4 hours, and veneer moisture contents of up to 15%. Both shear strengths and wood failure were comparatively high even after 5 weeks in water at 25 °C. 

One day after the flakeboards were made, the oak flakeboards having a 120 seconds press time were used to laminate with 1/8 southern pine veneers on face and back to form the 1/2 composite panel by the plywood resin. After 20 minutes close assembly time, the panels were hot pressed at a platen temperature of 300 F for 2 or 3 minutes under 200 psi platen pressure. 

Closed assembly time interval between assembly of the adhesive joint and the initiation by heat and/or pressure of the setting process in the assembled joint. 

Closed Assembly Time See Assembly Time, Assembly. 

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