Mold cleaning

Molds can be made from either metallic or nonmetallic materials. Metallic and nonmetallic molds are heated to the same temperature, which can be up to 120°C. Metallic molds are much more heat conductive than molds made from polyurethane or epoxy. When handling the metal molds, clean, heat-resistant gloves must be worn to prevent burning of the skin. The weight of these molds must be taken into account when handling them. Suitable lifting equipment such as a crane, block and tackle, or a forklift must be used. 

Examination of the economic data Indicates several specific areas where PU-RRIM 1s penalized, among them are long cycle time, process Inefficiency (down time for mold clean), scrap, and the need for external mold release. These factors result in higher labor, unit capital and tooling costs for PU-RRIM when compared to Injection molding. This situation provides a challange to make PU-RRIM more economically viable. 

Such RIM IMR technology has been developed by Dow and 1s 1n the final stages of production qualification at major RIM molders. While the details of this technology are beyond the scope of this paper, the impact of an effective IMR on RIM economics can be addressed. This data 1s shown on "Table X", where one can see cycle times reduced from 120 seconds to 90 seconds the elimination of nonproductive mold cleaning time and the elimination of scrap resulting from external mold release buildup. The reduction in part cost 1s significant the unit cost for the body panel is reduced from 11.72 to 9.55 for an 18.5% production cost reduction. 

Another place where dual packaging also comes into play is the use of peroxide for mold cleaning. Peroxide has a higher oxidation potential than hypochlorite (-1.36 eV for sodium hypochlorite and —1.8 eV for hydrogen peroxide), but paradoxically does not work with the speed of hypochlorite on bathroom mildew. However, peroxide has essentially no odor, in contrast to hypochlorite that has a distinctive and unpleasant odor. Without activation, peroxide bleach would take longer to do the job that hypochlorite does more quickly. One patent, therefore, incorporates an activator into a peroxide mold cleaner, but puts the formulation into a dual-chamber package so as to ease the job of stabilizing the formula on the shelf [349],... 

Potential adverse effects adhesion to hot metal surface, bubbling, increased mold cleaning frequency, lack of adhesion in joining processes, residue on the product surface, transfer to a material in contact, welding impairment... 

Chem. Descrip. N-Methyl pyrrolidone CAS 872-50-4 EINECS/ELINCS 212-828-1 Uses Solvent, cosolvent In coatings, stripping/cleaning of paints/vamishes. Industrial cleaning, mold cleaning, petrochem. processing solvent for adhesives, inks, dyes, soaps, metal complexes, agric. solvent for PVAc, PVDF, PS, vinyl copolymers, nylon and aromatic polyamides and polyimides, polyesters, acrylics, PC, cellulose derivs., syn. elastomers, waxes... 

MOLD CLEANING CLEANING HAZARD DISPOSAL OPERATE DAMAGE... 

HMIS Health 1, Flammability 0, Reactivity 0 Storage Moisture-sensitive store in cool, dry place keep containers sealed Uses Mfg. of effervescent salts and beverages, artificial mineral water prevention of timber mold cleaning preps. blast cleaning lab reagent antacid mouthwash OTC drug active ... 

PPG-2 methyl ether PPG-3 methyl ether PPG-2 methyl ether acetate solvent, moisturizing cleansers Octyidodecyl isostearate solvent, mold cleaning N-Methyl-2-pyrrolidone solvent, mold release agents Butyl lactate solvent, motors 1,1,1-Trichloroethane solvent, mouthwashes... 

Aero-Clean, Granulated acrylic mold cleaning media, Maxi-Blast, Inc. 

Matrax, Thermoplastic olefinic elastomers, M.A. Industries Inc., Polymer Div. Matrimid, High-temperature matrix resins, Ciba Specialty Chemicals, Performance Polymers MatVantage SMC, Needled mat for SMC, PPG Industries, Inc., Fiber Glass Maxi-Clean, Granulated melamine mold cleaning media, Maxi-Blast, Inc. 

Simichrome Polish, Mold cleaning compound, Competition Chemicals... 

Mold cleaning Seconding coating Gel-coat application Strengthening... 

Mold cleaning is generally done after several hundred shots, but befcne bad mold release or mold stain is observ l. Longer intervals between mold cleaning are desirable. 

An inexpensive elastomer mold is characterized by low life-cycle costs, which means long periods of time between necessary mold cleaning, long service life, and robust process windows at relatively low purchase prices. The selection of the correct process, the optimal rheological and thermal design, the use of suitable steel and the precise manufacture of the relevant (function-determining) dimension, as well as the suitable coating lead to the optimal result in the elastomeric mold manufacture. 

Application of mold release agent always bears a risk of cycle time increase (application of mold release and mold cleaning), cost increase (time and cost of release agent), variable surface quality (differences in adhesion dependent on the quality of mold coverage by release agent), and surface buildup with related negative phenomena such as plateout and/or variable adhesion. The very notion of the... 

Figure 193 Reaction injection molding (RIM). The Kraus-MafFei mixing head is shown in the shot position. At the end of the shot, the plunger moves down, packing the mold, cleaning the mixing chamber, and recirculating the reactant streams back to their storage tanks.

---