1.4 Forming, redistribution and addition processes

100 practice flashcards covering forming, redistribution, addition, and wasting processes for paper, board, polymers, metals, and woods based on the lecture notes.

What is the primary function of die cutters in paper and board forming?

To cut out paper or card 'nets' or 'developments' that form 3D shapes like boxes.

What components are inserted into the plywood substrate board of a steel die cutter?

Steel cutting dies and creasing rules.

How do creasing rules differ from cutting dies in a die cutting machine?

Creasing rules are lower in height and blunt, so they score the material without cutting it.

What is the purpose of rubber pads fixed to the press in a die cutting machine?

To help prevent the paper or card from sticking as the press moves up or down.

Why is laser cutting suitable for prototype construction or small-scale production?

Because it can cut, engrave, perforate, and carve quickly, accurately, and with high detail without a plywood die board.

What are common 3D products produced using vacuum forming?

Lightweight trays, box inserts, liners, coffee cups, and yoghurt pots.

What is the typical thickness limit for polymer sheets used in vacuum forming?

$$6\,mm$$

What is a 'draft angle' and why is it necessary for a vacuum forming mould?

A small angle on the mould that allows it to be removed from the polymer sheet once formed.

What material are moulds typically made of for high-quality, large-scale vacuum forming?

Cast and machined aluminium.

How does thermoforming differ from basic vacuum forming?

It uses an additional positive mould that is pressed onto the surface of the polymer sheet simultaneously with the vacuum.

What are two industrial applications for calendering?

Smoothing/rolling paper and making thin polymer sheet or film as stock material.

What is the process of heating thermoplastic pellets to a dough-like consistency and extruding them through rollers called?

Calendering.

What specific products are typically made using line bending?

Acrylic boxes, shelves, or point of sale displays.

What is the lay-up lamination process used to create?

3D products from fibre-based composites such as GRP or CFRP.

What is a 'gel coat' in the GRP lay-up process?

A coating of polyester resin mixed with pigment to give color and provide protection from UV and hydrolysis.

What is 'stippling' in the lamination process?

Using a small roller to push out air bubbles and smooth out the fibreglass matting.

Why is injection moulding usually reserved for large-scale mass or continuous production?

Due to the high cost of the equipment and the moulds.

How is molten polymer hardened quickly in an injection mould?

The mould is water cooled.

What specific components might be included in an injection moulded product?

Integral clip fastenings, screw posts, battery housing, and circuit board holders.

What is a 'parison' in blow moulding?

A tube of extruded melted polymer.

What advantage does injection blow moulding offer over standard blow moulding?

A greater level of tolerance, especially for components like threads.

Which process is used for making heavy-duty, seamless hollow objects like traffic cones or water tanks?

Rotational moulding.

What is the typical rotation speed used in rotational moulding?

Fewer than $20$ rotations per minute.

What is the specific temperature range for the oven in rotational moulding?

$$260 - 370\,^\circ C$$

What process is used to produce solid rods, hollow tubes, and 'I' or 'T' sections in polymers?

Extrusion.

What materials are commonly used in compression moulding?

Thermoset polymers such as urea formaldehyde and melamine formaldehyde.

In compression moulding, what is the term for the pre-weighed thermoset polymer charge?

A 'slug'.

What is 'flash' in the context of compression moulding?

Excess polymer that is removed after the moulding has cured.

What are metal 'forming processes'?

Processes in which no material is removed, but the material is deformed to produce required shapes.

Which metal forming process is used for car body panels and metal seats?

Press forming.

What materials are typically used in press forming due to their malleability and ductility?

Medium carbon steel and aluminium.

What technique is used to machine press forming dies from hardened steel?

Spark erosion.

What is spinning as a metal process?

A method of shaping objects with radial symmetry by pushing a rotating sheet of metal over a former or mandrel.

How can products made by spinning be identified?

By parallel lines formed on the surface of the metal during the process.

What is the difference between cupping and deep drawing?

It is considered deep drawing when the depth of the pressing exceeds the diameter.

Why are the corners of the punch rounded in deep drawing?

To cause the metal to stretch rather than be sheared.

What products are commonly made with drop forging?

Spanners, pliers, and screwdriver shafts.

What is the benefit of drop forging for metal strength?

It maintains the internal grain structure of the metal.

What is 'recrystallisation temperature'?

The temperature below the melting point at which it is possible to change the size and shape of the grains in a metal.

What makes wrought iron suitable for forging and bending?

Its very low carbon content of less than $0.08\%$.

What machine is used for bending sheet or plate metal in industry?

A press brake.

What device in a press brake accurately positions the piece of metal for bending?

A back gauge.

What is the primary difference between hot rolling and cold rolling metal?

Hot rolling is done above the recrystallisation temperature, while cold rolling is usually done at room temperature.

What is a disadvantage of hot rolling metal?

The surface is coated with carbon deposits that must be removed using acid pickling.

Why is cold rolled metal used for products like filing cabinets and home appliances?

It has a tighter tolerance and a much better surface finish due to the lack of carbon deposits.

What is a foundry?

A specialist factory where the sand casting process is carried out.

What type of surface finish does sand casting produce?

A low-quality, grainy texture picked up from the sand.

In sand casting, what are the names of the bottom and top boxes of the steel frame?

The drag (bottom) and the cope (top).

What is the purpose of the riser in metal casting?

To indicate to the worker that the cavity is full when the molten metal flows up it.

Why is die casting limited to lower melting point metals like aluminium and zinc-based alloys?

Because the reusable moulds are made from tool steel.

What are the two forms of pressure die casting?

Hot chamber and cold chamber.

Why is aluminium not cast using the hot chamber pressure die casting process?

It picks up iron from the steel chamber.

What are the primary applications for investment casting?

Intricate or awkward shapes like cast jewellery, collectable figures, and hip replacement joints.

What is the 'lost wax' process for investment casting?

Creating a wax pattern, coating it in refractory clay, firing it to burn the wax away, and then filling the hollow clay mould with metal.

Why is pewter ideal for school projects or commercial crafts?

It has a low melting point and it is easy to make moulds from various materials.

What is the definition of 'addition' in manufacturing?

Making components and products by adding pieces together using permanent or temporary joining methods.

What does MIG stand for in welding?

Metal Inert Gas.

What is the role of inert gas in MIG and TIG welding?

To form a 'flux' shield that replaces oxygen and prevents oxidisation at the joint area.

How does TIG welding differ from MIG welding regarding the electrode?

In TIG, the tungsten electrode does not melt; a separate filler rod is used.

At what temperature does the flame in oxy-acetylene welding typically burn?

$$3,500\,^\circ C$$

What is brazing also known as?

Hard soldering.

What material is a brazing filler rod usually made from and what is its melting point?

Brass; it melts at $850\,^\circ C$.

What type of solder is an alloy of tin and lead ($60/40$)?

Electrical solder.

Why are lead solders being phased out?

Due to their toxicity.

Describe the traditional cold riveting process.

Two pieces are overlapped and drilled, a rivet is inserted, and the shaft is hammered over a 'set' tool to squeeze them together.

When is pop riveting particularly useful?

When the underside of the joint is inaccessible.

How does a self-tapping screw function?

It has a coarse hardened steel thread that cuts its own thread when screwed into a pilot hole.

What characterizes machine screws?

They have a metric thread running the entire length of the shaft and are used to join thicker pieces of metal.

What is the purpose of a nyloc nut?

It has a nylon collar insert that deforms over the bolt thread to prevent the nut from coming undone through vibration.

What are the three movement directions for a milling machine table?

x (left and right), y (forwards and backwards), and z (up and down).

What materials are cutting tools on a lathe usually made from?

High-speed steel or tungsten carbide.

How does flame cutting pierce metal?

By introducing an additional jet of oxygen once the metal is heated to form a melt pool.

What is the temperature of the heat generated by a plasma cutter?

Up to $28,000\,^\circ C$

What are the three main components of a plasma cutter system?

Power supply, arc starting console, and plasma torch.

In laser cutting, what is used to focus the laser into a fine beam?

A focal lens inside the laser head.

What is 'nesting' in CNC punching?

Using software to establish the most efficient layout of parts from a given sheet to minimize waste.

What is the simplest method for joining two pieces of timber?

A butt joint, which relies solely on adhesive.

Why is a dowel joint stronger than a butt joint?

Because the hardwood dowels interconnect the two pieces.

What joint is commonly used to make picture frames?

A mitre joint, cut at $45^\circ$ to make a $90^\circ$ corner.

Which joint is characterized by interlocking 'combs' and used for box construction?

A comb or finger joint.

Why are dovetail joints ideal for making drawers?

They have directional strength and are impossible to pull apart once glued.

What are the components of a mortise and tenon joint?

A rectangular hole (mortise) and a matching projecting end (tenon).

What joint is commonly used for framework, cabinets, and shelving by cutting a groove across one piece?

A housing joint.

What are KD fittings?

Knock-down fittings, used for the manufacture and easy assembly of flat-pack furniture.

What is a cam-lock connector?

A KD fitting consisting of a metal dowel and a disk (cam) that locks the pieces together when rotated.

What is the 'shank' of a wood screw?

The part of the shaft that does not have a thread.

Which type of wood screw head was developed specifically for better contact with power tools?

Pozidriv.

What feature of a coach bolt prevents it from rotating when being tightened?

A square piece under the domed head that digs into the wood.

What are the three methods for wood turning on a lathe?

Turning between centres, turning on a faceplate, or turning in a chuck.

What tool is used for handheld wood turning to reduce diameter?

Gouges and scrapers.

What can a portable electric plunge router be used for in timber machining?

Making slots, holes, or decorative mouldings on edges.

What are the two main methods for forming timber into curves?

Lamination and steam bending.

How is pressure applied in wood lamination using a vacuum bag?

A vacuum pump sucks out the air under a polythene sheet, pulling the laminates together.

What makes wood pliable during steam bending?

The combination of heat and steam absorbed in a steam box.

What are the properties of Polyvinyl acetate (PVA) adhesive?

It is a white, water-based adhesive that soaks into the wood surface and sets as moisture is absorbed.

When is contact adhesive typically used?

For bonding large surface areas of the same or different materials together instantly without clamping.

What does a UV hardening adhesive contain to enable it to set when exposed to light?

A photo initiator.

How does solvent cement join polymers like acrylic?

It softens the surface of the polymers, allowing them to fuse together; an example is Tensol 12.

What is the difference between a jig and a fixture?

A fixture holds work in a given position; a jig holds the work and also guides a tool.

What is an example of a specific wood jig used for cutting 45 degree angles?

A mitre block.