体积变化矩阵，也称为产品过程矩阵，是一个用于演示产品体积的模型。矩阵最初由Wheelwright和Hayes(1979)设计。他们认为这是一种方式，通过这种方式可以表示产品和过程周期的交互作用(Hayes & Wheelwright, 1979)。用一个作者的观点从两个矩阵维的生命周期的角度来看待它们的原始形式。这是因为有意将过程进展显示为一个可预测的生命周期，并且与所理解的产品生命周期概念(产品开发和生命周期，1988)相对应。自从产品过程矩阵问世以来，该模型就被用作显示产品或产品集合的不同操作需求的一种方式。被收集的产品具有不同的竞争力特征，并有一种列举由于未能匹配工艺和产品特性/特性而导致的后果的方法(Hayes & Wheelwright, 1979)。
公司所处的区域完全由公司在产品生命周期和生产过程中对公司的选择方面所处的阶段决定。占据矩阵左上角的公司被定义为倾向于一个聚焦方向的过程。另一方面，那些位于矩阵右下角极端的公司是通过确定生产系统是由过程中的集团资源构成的还是由产品构成的来管理的。矩阵顶点产生四种不同的操作类型，这些操作通过位于矩阵对角线上的过程的正确选择来描述，如下图所示(Ahmad & Schroeder, 2002)。
The volume-variety matrix also known as product-process matrix is a model used in the demonstration of the volume of a product. The matrix was devised originally by Wheelwright and Hayes (1979). They saw this as a way through which an interaction of the product and process cycles could be represented (Hayes & Wheelwright, 1979). The original form of the two matrix dimensions were viewed in their life cycle terms with one author. This is because of having the intention to show process progress as a life cycle that is predictable and corresponding to the understood product life cycle concept (Product development and life cycles, 1988). Ever since the product-process matrix came to light the model has been adopted as a way of showing the varying operational requirements of products or collection of products.The products which are to be collected have the property of bearing different characteristics on competitiveness and a way of enumerating consequences resulting from failure to match process and product characteristics/properties (Hayes & Wheelwright, 1979).
Product Process Matrix
The region occupied by the company is entirely governed by the stage at which the firm is in terms of the product life cycle and the choice of firm in the production process.Firms occupying the top left region of the matrix are defined as processes leaning towards a focused direction. On the other hand, those firms at the bottom right extreme of the matrix are governed by determining whether the system of production is structured by group resources in the process or by the product. The matrix vertices yield four types of distinct operations that are described through the correct choice of process that is located at the matrix’s diagonal as illustrated below (Ahmad & Schroeder, 2002).
The inclusion of projects as a component of the matrix is merited and found at the top left side of the matrix. The inclusions of one time, large scale and unique products like the aerospace programs, engineering contracts and construction etc. define the projects category.These types of projects are usually specific to the customer needs and are monumental to be removed. This in essence means that such projects are the process choices.