Tooling is a general term to describe any custom made items that are created to form, shape or create parts and pieces of your product. NRE is short for non-recurring engineering, which is a bit of deceiving title. When most people hear engineering they think it's the people who design the parts in software. In this case NRE are all the specific materials that are necessary to manufacture and assembly your product. It is things, not man hours.
This most commonly are tools and dies. If you are having custom plastics made then 99 percent of the time you'll need one or more plastic tools made. The hollow part where plastic is injected is called the cavity. It is very important for you to think about how many parts you will be manufacturing over a period of time. This tool is fitted to a molding machine and allows hot plastic material to be injected and pressured and then ejected when the part is formed and completed. The process of the injection, formation and ejection of the part usually only takes a few seconds and is almost always automated.
When you have a tool made you have to decide how many cavities will be in the tool. If you create a double cavity tool of the same part the injection machine will produce parts twice as fast. If you have a four cavity mold made of the same part then the injection machine will eject parts four times as fast. Why does this matter? Machine time on an injection molder costs money to both setup and calibrate and to run. It will also gauge your parts availability which impacts your production run times. Injection machine setup usually runs from $200 to $500 each time. The effort for setup involves a fork lift to get you metal tool in place out of storage, connection to the injection molding machine, connection of your plastics materials and then usually several hours to run selected parts and inspect and adjust the injection molding machine. It can take a very long time for an injection machine to create a large quantity of plastic parts with only a single cavity. If you are going to need hundreds of thousands of parts at a time, a single cavity tool will not be enough production capacity. You can also sometimes make different shaped parts out of the same tool. This is called a family tool. Family tools allow different parts to be made at the same time from the injection molding machine. Not all parts can be part of a family tool. For example it can be very difficult to make very small parts along with larger parts because the amount of pressure to fill the cavities can be very different. In this case the injection machine will overfill one cavity or under fill another. The parts need to be made from the same plastic material. A family tool has the same advantages in saving setup fees and machine time. BUT, adding cavities to a tool costs more money - usually about 30 percent more for the same tool.
In general, expect to pay tens of thousands of dollars to over a hundred thousand dollars to have plastic tooling made. How much the exact cost will be needs to be costed out by tool and die maker. You really can't get an exact quote until the CAD (computer aided design) files are sent over to them. They will review the computer files and have a conversation about the injection points in the tool and the ejection points. The injection is where plastic materials is shot in the cavity and the ejection point is where metal pins push on the shaped plastic to eject it out of the cavity. These two points can leave marks or scoring and you'll need to work with the tool and die company to make sure those marks don't impact the visual aesthetics of your product or hamper the ability to assemble the pieces. They will also need to discuss small complex fill areas that may be difficult to get proper injection or complete fill of material.
Overmolding is a process by which two different materials are created together in one tool. For example you may have a rigid plastic part that has a window in it for an electronic switch. To protect the switch you can overmold a softer plastic that will protect the switch from dirt or liquids but still allow the switch to be depressed. Overmolding requires additional design consideration, plastics material selection and more complicated tooling. It can also take more time to work with and adjust both the tool and the injection molding machinery in order to get the parts to be completed correctly.
Don't forget that you can create imprints on your tooling to do things like brand the part, make indelible identification numbers (parts numbers, FCC certifications, etc.) or include simple directions (top, bottom, etc.). Instructions can be great for assembly to reduce errors and often it can be on the inside of your product so end buyers never see them. Imprinting can also save you label costs and the expense to adhere labels.
Types of Material for a Tool
The material you make your tooling to be created out of also impacts the price. If you are only looking to make tens of thousands of pieces then you can consider "temporary tooling". This is usually a tool shaped out of a block of aluminum which is a soft metal. It takes far less time to manufacture an aluminum tool instead of a hardened steel tool because of its softness. You can save as much as 30 percent on your tooling costs by using this kind of tool. The negative is the software metal wears out faster making parts. Often people get away with hundreds of thousands of parts out of an aluminum tool but no one will guarantee that kind of performance. Steel tooling generally is more expensive but should get you at least 1 million parts produced. Sometimes you'll get a couple million parts out of a steel tool.
Here is another note, not all tools will fit on all injection molding machines. They have connection and locking points in the metals that may not match. This is a type of base. If you are having tools made in the US or Asia and you plan on moving them at some point to a different manufacturer you need to verify base compatibility. It is important as you go through the process of setting up for manufacturing that you coordinate your engineering, tool and die maker and plastics parts manufacturing. To do otherwise is to look for trouble.
US tooling verses Asian tooling
You can get tooling made in Asia cheaper than the US. It can cost as much as half in Asia BUT there is always a challenge in getting the tool finalized and you may have quality concerns. Also sometimes you really don't know where in Asia your tool lives. It can be in a sweat shop in the backgrounds of a third world country. Good luck getting that back if your manufacturer goes out of business or refuses to work with you any more. I know of manufacturers that are having tools made in Asia, shipped to the US and then having them "corrected" here in the states. The total cost savings average seems to be about 25 percent, but it adds several months to the time to have a completed tool working in the US. When it comes to spitting out plastic parts there is very little savings in having plastics manufacturing done in Asia verses the US. Making plastics is about machines and not about labor. I know many US based plastics manufacturers that have no problem competing against Asian competitors.
Correcting or Changing Plastic Tooling
You definitely do not want to create prototype parts with full plastic tooling. It is expensive and time consuming to change a full metal tool. Rapid prototypes are the way to go initially or through the creation of SLA molds that get you only one or a couple of the items. The problem is alterations in final tooling is expensive, time consuming and could wreck your very expensive tool.
If you do need to make an alternation in your final tooling it is usually far easier and cheaper to take away material (increase the size or dimensions of the parts) than it is to add material (decrease the size or dimensions of the parts). In either case it really should be a course of last resort since alterations to a tool could ruin it. If that happens you need to start all over and you doubled your plastic tooling costs.
Stencils, Stamps and Dies
Stencils are outlines of patterns that you need to imprint on a part or a material to a specific shape. You may also use stencils to overlay materials on top of each other. A die and a stamp is used to cut and shape materials. Usually stencils, stamps and dies are used together. For example, if you're creating circuit boards you'll need a die to cut the circuit board to a shape (called green board because of its color) and they will use a stencil to lay the electric conducting traces on the board. You use stencils and dies for things like cutting cardboard to shape for a particular box, stamping out holes in faceplates for buttons and switches to protrude or cutting shapes to custom labels or notices. Stamps are mostly used for shaped metal. A simple stamp will cut flat "square" metal instead a custom shape. More sophisticated stamps will cut metal so a machine can fold, bend, extrude or shape the material. In general it costs from a couple hundred to a couple thousand dollars to have a stencil, stamp or die created. The more sophisticated the part the more expensive the item.
NRE - Non-Recurring Engineering
In general, each part that is custom created and assembled needs to be examined for "how do I put this together" in the right way, with the right quality, every time in the fastest way. This is where non-recurring engineering comes in.
Custom products require special parts, machines, test equipment, etc. for a manufacturer to create, test, assemble and box your product. Some items you can expect and plan for upfront. For example, you need your product to be in packaging. Once you've selected the type of packaging you want then tools, dyes or stamps can be created to cut cardboard, shape plastic, etc. Other items won't be determined until the full engineering documents are sent to the manufacturing engineers and/or they built prototypes or first articles (first finished product). Manufacturing engineers may be degreed engineers or they may simple hold that title. Do not expect them to discuss and improve the design or your product. That is what your research and development engineers are for. They are there to figure out how to actually make your product. This is practical engineering. Sometimes your R&D and manufacturing engineers are going to end up at odds on problems and challenges.
All sorts of things need to be created depending on your product:
Fixtures are used to hold parts during assembly. They can be linked to computers and robotic or they can be manual and manipulated by a human operator. If you are soldering metals together then usually you need something to hold the parts in place while this is done.
Electronics require fixtures which program chips and test electronic components on a circuit board. Circuit boards are placed with electronics with multiples on a sheet. So custom fixtures touch all of the same parts placed on different locations at the same time. This is done through a machine on an assembly line. A programmer needs to custom program for testing and for chip programming. Custom fixtures cost thousands of dollars each and can take weeks or months to get right.
Jigs are common to create for assembly. A jig is a custom device that allows different components to lay out in a specific way and be held during assembly. Jigs can cost from a couple hundred dollars to thousands of dollars to create.
Assembly and testing machines can run the gambit from robotic arms, sonic welders, laser scanners, xray machines, air compression machines, leak detectors, etc. Even a basic test machine is going to cost thousands of dollars to create and you'll need more than one made in case the first one breaks.
So there you have it in a nutshell. The basics of tooling and NRE. There is so much more to learn and depending on what you'll have made it can get much more sophisticated. Please remember to budget for NRE. Many people leave it completely off budgets and for moderately complex products it will cost you tens of thousands of dollars to have created.