Computer-Aided Manufacturing

Computer-Aided Design (CAD) is the use of software to create the precise 3D models and 2D drawings of a part and its mold. In injection molding, CAD is where every project begins: the molded part is modeled in CAD, then that model drives mold design, machining and simulation. The 3D file is the single source of truth that the whole tooling chain works from. ## Role in the molding workflow - Part design: the geometry — walls, ribs, bosses, draft and former holes — is defined in CAD, applying design for manufacturing and design for assembly rules before any steel is cut. - Mold design: the cavity and core, runners, cooling lines, ejectors and slides are modeled in CAD around the part, including shrink compensation. - CAD → CAM: the CAD model feeds CAM (computer-aided manufacturing) to generate CNC toolpaths that cut the mold. - CAD → CAE / flow simulation: the same model feeds mold-flow analysis (CAE) to predict fill, weld lines, sink and warpage and refine gating before cutting steel. ## Why it matters A clean, manufacturable CAD model prevents expensive surprises: errors caught on screen cost minutes, errors caught in hardened steel cost weeks. CAD also carries tolerances and GD&T that feed inspection and a quality system, and lets revisions propagate to the mold, the molding process setup and documentation. ## Related terms - See also: molded part, design for manufacturing, design for assembly, former holes, cavity ## What is CAD in injection molding? Software used to model the part and the mold in 3D; the CAD file defines the geometry and tolerances and then drives mold design, CNC machining (CAM) and flow simulation (CAE) throughout the tooling process. ## How is CAD used to design an injection mold? The molded part is modeled first, then the mold — cavity, core, runners, cooling and ejection — is built in CAD around it with shrink compensation, and the model is sent to CAM for machining and CAE for flow analysis. ## What is the difference between CAD, CAM and CAE? CAD creates the 3D geometry; CAM turns it into CNC toolpaths to machine the mold; CAE (e.g. mold-flow analysis) simulates how the plastic fills and the part behaves — all working from the same CAD model.

CNC (Computer Numerical Control) is the technology that lets a machine tool follow programmed toolpaths via an electronic controller that interprets G-code and M-code. In the molding industry, CNC machines are what cuts the plates, cavities, cores and inserts of the mold. ## CNC in mold manufacturing The CNC controller drives the linear axes (X, Y, Z) and rotary axes (A, B, C) along programmed coordinates, holding tolerances of ±5 to ±50 µm in finishing operations. Accuracy depends on machine rigidity, spindle quality, position sensors and ambient temperature of the shop. ## Common CNC machines for moldmaking - 3-axis vertical machining centers (VMC) for plates - 5-axis centers for complex cavities and undercut access - CNC lathes for cylindrical inserts and cores - Wire EDM and sinker EDM for fine details - CNC grinders for sub-micron tolerances ## Programming and communication G-code programs are produced in CAM and transferred via Ethernet, USB or DNC. Common controllers: Heidenhain TNC, Fanuc, Siemens Sinumerik, Mitsubishi and Mazatrol. Each uses slightly different G-code dialects. ## Frequent issues Crashes from simulation errors, thermal drift in spindles, uncompensated tool wear, and part-zero errors. They are mitigated with touch probes, spindle-load monitoring and preventive maintenance.

Mold (Tool) is the mechanical assembly of plates, cavities, injection system and cooling that shapes the molded part. It is the single most expensive asset of the operation (10,000 – 500,000 USD) and its design dictates everything: cycle, quality, productivity and unit cost. ## Main components - Cavity plate (fixed half): nozzle side, usually houses the cavity - Core plate (moving half): ejector side, holds the core and ejector pins - Injection system: sprue, runners, gates (cold or hot) - Cooling system: water/glycol channels, conformal in premium molds - Ejection system: pins, sleeves, stripper plates, slides for undercuts - Standard components: leader pins, bushings, retainers, sensors - Replaceable inserts in wear areas ## Mold types - Single-cavity: prototypes, large parts, low production - Multi-cavity (2/4/8/16/32+): mass production - Family mold: different cavities for parts of the same assembly - Cold runner: with cold runners separated each cycle - Hot runner: no runner scrap, shorter cycles - Stack mold: two levels of cavities to double capacity - Two-shot / multi-material: two resins in the same part ## Mold materials - P20 (pre-hardened steel): standard for medium production, easy to machine - H13: hardened inserts, high thermal-wear resistance - S136 (stainless): polished cavities, corrosion resistance (PVC, PET) - Aluminum (7075): prototype or low-volume molds - NAK80: mirror polish without distortion ## Typical service life - Aluminum: 5,000 – 50,000 cycles - P20: 100,000 – 1,000,000 cycles - Hardened H13: 1 – 10 million cycles - Carbide / TZM in hot-runner gates: up to 50 million ## Critical maintenance Cleaning after every production run, vent inspection, lubrication of pins and guides, monitoring of cooling channels (scaling), and repair of cavity damage before it spreads.