PDT 317-INJECTION MOLD DESIGN MOULD MATERIAL PREPARED BY: EN. SHAYFULL ZAMREE BIN ABD RAHIM Email: shayfull@unimap.edu.my (019-4728377)

STEEL FOR INJECTION MOULDS PDT 317-INJECTION MOLD DESIGN STEEL FOR INJECTION MOULDS The cost of the steel in a mould usually represent only 5-10% of the total cost. Important thing to consider in mould steel selection How important is the surface finish? Does it need to be a mirror or optical finish? Will the mould for the part be patterned by photoetching? Will the moulding material be corrosive, abrasive or both? How critical is it that tolerances are held within close limit? What quantities have to be produced?

STEEL FOR INJECTION MOULDS PDT 317-INJECTION MOLD DESIGN STEEL FOR INJECTION MOULDS Most commonly used Steel for Injection Moulds: Pre-Hardened Mould Steel Through-Hardening Mould Steel Corrosion Resistant Mould Steel

STEEL FOR INJECTION MOULDS PDT 317-INJECTION MOLD DESIGN STEEL FOR INJECTION MOULDS When to used Pre-hardened Steel? These steel are mostly used for: Large Moulds Moulds with low demands on wear resistance Usually within 290-370 Britnell range. The surfuce hardness car be increased in many cases by flamehardening or nitriding Prehardened mould steels are generally used for large moulds and for moulds with moderate production runs. Example: ASSAB 618 & 718

STEEL FOR INJECTION MOULDS PDT 317-INJECTION MOLD DESIGN STEEL FOR INJECTION MOULDS When to used Pre-hardened Steel?

STEEL FOR INJECTION MOULDS PDT 317-INJECTION MOLD DESIGN STEEL FOR INJECTION MOULDS When to used through hardened Steel? These steel are mostly used for: for long productions runs to resist abrasion from certain moulding Materials to counter high closing or injection pressures. They are usually rough-machined, stress relieved, finish-machined, hardened and tempered to the required hardness and then finish-ground and often polished or photoetched.

STEEL FOR INJECTION MOULDS PDT 317-INJECTION MOLD DESIGN STEEL FOR INJECTION MOULDS When to used through hardened Steel? (Continued…) Obtain better wear resistance, resistance to deformation and indentation and better polish ability. Better wear resistance is especially important when filled or reinforced plastic materials are used. Resistance to deformation and indentation in the cavity, gate areas and parting lines helps to maintain part quality. Example: STAVAX and 8407

STEEL FOR INJECTION MOULDS PDT 317-INJECTION MOLD DESIGN STEEL FOR INJECTION MOULDS When to used through hardened Steel? (Continued…)

STEEL FOR INJECTION MOULDS PDT 317-INJECTION MOLD DESIGN STEEL FOR INJECTION MOULDS When to used through corrosion Steel? It has been developed to meet the requirements from producers of such high-tech products as CDs, memory discs and lenses. STAVAX, a corrosion resistant mould steel offering excellent polishability combined with good machinability. OPTIMAX is also a corrosion resistant mould steel and a further development of STAVAX when it comes to polishability ELMAX, finally, is a powder-metallurgy mould steel with high wear and corrosion resistance.

STEEL FOR INJECTION MOULDS PDT 317-INJECTION MOLD DESIGN STEEL FOR INJECTION MOULDS When to used through corrosion Steel?

STEEL FOR INJECTION MOULDS PDT 317-INJECTION MOLD DESIGN STEEL FOR INJECTION MOULDS

STEEL FOR INJECTION MOULDS PDT 317-INJECTION MOLD DESIGN STEEL FOR INJECTION MOULDS

STEEL FOR INJECTION MOULDS PDT 317-INJECTION MOLD DESIGN STEEL FOR INJECTION MOULDS The properties of the mould have been rated from l- 10, where I0 is the highest rating. Such comparisons must be considered approximate but can be a useful guide to steel selection.

PDT 317-INJECTION MOLD DESIGN MOULD MATERIAL

PDT 317-INJECTION MOLD DESIGN Insert Size The selection of an appropriate mould base is based on the depth of the part, its projected area and the number of cavities required in the mould Extra allowance has (7.5cm) to be given for moulds with mechanical action side-pulls and other complicated mechanisms such as unscrewing devices for the moulding of screw threads The clearance between cavities and cavity to edge = 7.5cm The distance from edge of part to edge of insert is about 25-30mm To determine the appropriate mould base size for a particular part, it is necessary to imagine the moulded part embedded within the mould base plates

PDT 317-INJECTION MOLD DESIGN Photo Etching Photo etching, the most common metal etching process, is the process in which a desired image is etched on the surface of the metal part via a photosensitive template. The piece is then exposed to an appropriate acid (or etchant) that removes a layer of metal in areas left unprotected by the template, after which the piece is cleaned and the photoresist template removed. A variety of metals can be photo etched, including stainless steel, beryllium, copper, copper alloys, brass, nickel, silver, kovar, and many others.

PDT 317-INJECTION MOLD DESIGN Photo Etching

PDT 317-INJECTION MOLD DESIGN Engraving

Heat Treatment – Flame Hardening PDT 317-INJECTION MOLD DESIGN Heat Treatment – Flame Hardening This process involves direct an oxy acetylene flame on the surface of the steel being hardened and heating the surface above the upper critical temperature before quenching the steel in a spray of water. This is also known as the shorter process. This is a surface hardening process resulting in a hard surface layer of about 2mm to 6mm deep. The main difference between this process and other surface hardening processes is that the composition of the steel being hardened is not changed. The steel must itself have sufficient hardenability . This limits this process to steels having carbon contents of above 0.35%. Steels with carbon contents of 0.4% - 0.7% are most suitable for this process. Steels with higher content and high alloy steels may not be suitable as they a liable to cracking. 

Heat Treatment – Flame Hardening PDT 317-INJECTION MOLD DESIGN Heat Treatment – Flame Hardening

PDT 317-INJECTION MOLD DESIGN Nitriding Certain steel alloys can absorb nitrogen with a resulting extremely hard surface layer.   The process consists of maintaining the steel component at a carefully controlled temperature of 490oC to 530oC under the action of nascent of active nitrogen produced on the surface of the component by the decomposition of gaseous ammonia.  The resulting surface is extremely hard and extremely thin but very brittle.  The process time is about 90 hours and the temperature of the furnace has to be maintained within ±5oC and therefore electrical heating is generally used.   The components are generally stacked in gas-tight boxes supported on nickel mesh trays.  The boxes include a inlet and outlet pipes for the ammonia gas circulation flow.  Nitriding does involve small dimension increases of up to (0,05mm) on diameters and smaller amounts on individual flat surfaces and lengths. The nitriding process is also often followed by surface grinding to remove the most brittle outer layer.

PDT 317-INJECTION MOLD DESIGN Nitriding

PDT 317-INJECTION MOLD DESIGN Q&A

PDT 317-INJECTION MOLD DESIGN SEKIAN TERIMA KASIH