The key difference is that throughput is based on what is actually billed and delivered, while output is something produced and sitting in inventory providing zero value to the organization. Fundamentally throughput relates to cash flow, productivity and profitability; the key elements of any success factor of an organization.
Having throughput as a KPI measure provides the ability for any organization to achieve its goal; the goal of being profitable and ability to grow. The rest has no relevance.
Measuring throughput on its own provides limited value without linkages to the organizational elements resources, markets, teams and process which are all part of the system. Throughput is the outcome of a system. System Thinking considerations:
• A system is greater than the sum of its parts
• A system is not the sum of its elements/parts – it is the sum of their interactions. IT interacts with other areas. In order to maximize manufacturing, the objective is not output but rather throughput (what is made and sold). The parts that interact can be the following:
- Manufacturing Equipment, tooling
- Skilled resources
- Manufacturing execution system
- Manufacturing planning and control system
- Management structure
Fundamentally each one needs to consider how they interact with each other. The performance of the system depends on how well the parts fit together
Therefore to maximize throughput it is important to optimize the interaction between the various elements of the system.
Introducing multi-dimensional throughput KPI measurement , will ensure the visibility of direct contribution of related elements (the system) that have an impact on throughput:
- Manufacturing Plants
- Throughput for actual manufacturing site
- Productivity for actual manufacturing site
- Manufacturing equipment / System
- Throughput for actual key constraining resources
- Geographical area
- Product Brands
- Customer groups
- Organizational Teams
- Information Technology
- Supply Chain
• Throughput (T) is the rate at which the system produces "goal units." When the goal units are money (in for-profit businesses), throughput is net sales (S) less totally variable cost (TVC), generally the cost of the raw materials (T = S - TVC). Note that T only exists when there is a sale of the product or service. Producing materials that sit in a warehouse does not form part of throughput but rather investment. ("Throughput" is sometimes referred to as "throughput contribution" and has similarities to the concept of "contribution" in marginal costing which is sales revenues less "variable" costs - "variable" being defined according to the marginal costing philosophy.)
• Investment (I) is the money tied up in the system. This is money associated with inventory, machinery, buildings, and other assets and liabilities. In earlier Theory of Constraints (TOC) documentation, the "I" was interchanged between "inventory" and "investment." The preferred term is now only "investment." Note that TOC recommends inventory be valued strictly on totally variable cost associated with creating the inventory, not with additional cost allocations from overhead.
• Operating expense (OE) is the money the system spends in generating "goal units." For physical products, OE is all expenses except the cost of the raw materials. OE includes maintenance, utilities, rent, taxes and payroll.
Organizations that wish to increase their profitability should consider the following:
1. Increase throughput? How to increase, in what areas?
2. Reduce investment (inventory) (money that cannot be used)? How?
3. Reduce operating expense? How?
The answers to these questions determine the effect of proposed changes on system wide measurements:
1. Net profit (NP) = throughput - operating expense = T-OE
2. Return on investment (ROI) = net profit / investment = NP/I
3. TA Productivity = throughput / operating expense = T/OE
4. Investment turns (IT) = throughput / investment = T/I