Neck rings

In non-carbonated drinks there may be visible deposits, and sometimes a neck ring in the finished product, caused by agglomeration of smaller particles. Filtration of the incoming water stream is therefore essential. 

If vitamins are added to a product to make a nutritional claim, it is critical that shelf-life studies are undertaken to prove that the overages added are sufficient to ensure that the label claims can be met at the end of product shelf life. This is important as none of the vitamins are fully stable in a soft drink environment and some, for instance vitamin C, are very quickly lost in the presence of oxygen. The addition of the fat-soluble vitamins to a soft drink also offers a formulation challenge to ensure that they are fully dispersed and that there are no problems with neck ringing during storage. Trace metals, particularly the transition elements, can also have a deleterious effect on vitamin shelf life, and sometimes metal scavengers, such as EDTA or phosphate salts, are added to improve the shelf life. 

It is essential for QC to acquire the skills to differentiate between grades of defects and to be able to classify their usage implication, e.g. splits in bottles can be significant according to their length or depth as well as their position (in the neck, ring, shoulder, body, base, internal or external surface, etc.) and whether product is hot or cold filled etc. 

Injection blow-molding requires two molds one for molding the preform or pari-son, and the other for molding the bottle. The preform mold consists of the preform cavity, injection nozzle, neck-ring insert, and core-rod assembly. The blow mold consists of the bottle cavity, neck-ring insert, and bottom-plug insert (see Figs. 6-10). 

Fig. 7. Exploded view of one-half of a parison-mold cavity, with nozzle and neck-ring details.

The neck-ring insert has four functions (1) it forms the finish or threaded neck section of the bottle (2) because it is an insert, it provides a relatively low cost, easy method to change the size or style of the finish (3) it firmly centers and locates the core rod in the parison cavity and (4) it provides venting and a thermal break. 

Dining the process, the neck-finish area of the parison must be cooled to retain its shape the remainder of the parison is kept hot for later expansion in the bottle cavity. Depending on the plastic molding material, the temperature of the parison is between 65 and 135°C. The neck-ring insert is at times cooled as low as 5°C. The water lines for both the cavity and the neck-ring are usually drilled as closely together as possible, perpendicular to the cavity axis. The water flows from one cavity to the next. 

The neck-ring insert is used in the bottle cavity in a manner similar to its use in the parison cavity, although they are not identical. The thread diameter dimensions in the bottle cavity are 0.05-0.25 mm larger than in the parison cavity. 

Unlike the parison neck-ring, the hottle neck-ring does not form the finish detail, but only secures the already-formed neck. The additional size provides clearance, reducing the change of distortion. 

Aluminum, steel, or beryllium-copper is used for the bottle cavity and neck ring. For polyolefin resins, aluminum No. 7075, as well as QC-7, is used. The surface is usually finished with No. 120-grit sandblast, which increases the venting of trapped air. For rigid resins, A-2 tool steel air-hardened to 52-54 HRC is used. The surface finish is highly polished with chromium plating. Cast beryllium-copper is often used for minute detail. As with the parison cavity, water lines are drilled as closely together as possible, perpendicular to the cavity axis. 

In setting up the injection parison mold, a separate cooling line should he used for the neck rings, the parison end cap, and the zone immediately above the end cap. The temperature of the parison that is going to be blown needs to be controlled as imiformly as possible. If core-rod cooling is utilized, then a separate cooling unit should be utilized for the core rods. 

In the blow mold, a separate cooling line should be used on the neck rings, the bottom plug, and the containers body. 

Unlike injection blow molds, which are mounted onto a die set, extrusion blow molds are fitted with hardened-steel guide pins and bushings to ensure that the two mold halves are perfectly matched. Dies, mandrels, blow-pin cutting sleeves, and neck-ring striker plates are made from tool steel hardened to 56-58 HRC. 

Neck Mould or Neck Ring. The mould that shapes the neck of a glass bottle. 

CGA Pamphlet C-6 provides detailed instructions, and Appendix A provides a sample inspection report form. In general, all part of a cylinder (e.g., valves, neck rings, hoses, manifold, regulator, etc.) should be inspected, at a minimum, for ... 

Milling is used when intensive cooling by drilling channels is not achievable, for example, in the shoulder portion of blown bottles, recessed bottom parts, neck rings, and in preform molds for stretch blow molding. 

With dip biow moiding, the biow pin dips into the dip chamber [9j. After the neck ring is fiiied, the biow pin is puiied back. Axial variations in parison wall thickness can be achieved by programming the motion of the dip chamber piston. Figure 1.161 shows the production of the parison. The parison is then taken over by the blow mold, and the product is biown. After that, the blow pin is withdrawn, and the blow process is continued with an auxiliary blow pin. 

A controlled parison is one in which the dimensions are partially controlled through tension (i.e., the rotary wheel, the falling neck ring, etc.)... 

Tooling for injection blow molding consists of injection molding die set, injection molding manifold, parison injection molds, blow mold die set, blow molds, neck rings, core rods, face bars, end plates for the parison injection molds, secondary nozzles for the injection manifold, stripper bar, and retractable bottom plugs for the blow molds if the bottle push up exceeds 0.045 in. in depth. 

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