Tungsten Shot Pellets Density and Hardness Trade-off
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Solution Overview
Problem
Current nontoxic shot materials for hunting, such as steel, fail to replicate the high density and predictable ballistic characteristics of lead, leading to issues like reduced range, inferior pattern density, and increased barrel pressure, causing frustration and safety concerns for hunters.
Innovation Solution
Development of high-density, sintered tungsten shot pellets with precise control over size and sphericity, utilizing mechanical agitation and tumbling processes to achieve densities of at least 10 g/cm3 and Vickers hardness of 230 or less, and optionally coating with tin for added protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If steel shot pellets are used as a nontoxic substitute for lead, then toxicity is eliminated, but density decreases from 10-11 g/cm³ to 7.5-8.0 g/cm³
Solution Approach 1:
The invention changes the material parameter from steel to tungsten, which fundamentally alters the density characteristic from 7.5-8.0 g/cm³ to 10-16 g/cm³, matching or exceeding lead's density while maintaining nontoxicity
Solution Approach 2:
The invention uses composite materials by combining tungsten with binder materials and optional coating layers (tin, zinc, or copper), creating a composite shot pellet that achieves both high density and desirable mechanical properties including controlled hardness and reduced brittleness
2Speed
If larger gauge shot pellets are used to compensate for density difference, then trajectory performance improves, but pattern density deteriorates
Solution Approach 1:
By changing the material to tungsten with superior density, the invention allows use of smaller shot pellet sizes while maintaining trajectory performance, which in turn increases the number of pellets that can be loaded and improves pattern density
3Ease of manufacture
If steel shot pellets are used, then manufacturing cost is reduced, but ballistic performance deteriorates
Solution Approach 1:
The invention changes the material parameter to tungsten, which provides superior ballistic performance with density of 10-16 g/cm³ compared to steel's 7.5-8.0 g/cm³, while the sintering manufacturing process keeps production costs reasonable
4Quantity of substance
If tungsten shot pellets are sintered to high density, then ballistic performance improves, but hardness increases making them too abrasive
Solution Approach 1:
The invention uses composite materials by combining tungsten powder with binder materials during sintering, and optionally adding coating layers, which allows achieving high density (10-16 g/cm³) while controlling hardness to be no more than about 230 Vickers to reduce abrasiveness
Solution Approach 2:
The invention applies different properties to different parts of the shot pellet structure - the tungsten core provides high density while the binder and optional coating layers provide controlled hardness and reduced abrasiveness, creating local quality differentiation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The tungsten shot pellets provide consistent, high-quality ballistic performance, improved loading characteristics, and enhanced energy transfer upon impact, addressing the limitations of previous nontoxic materials while ensuring safety and effectiveness in hunting applications.
Implementation Method 1
The green balls are then sintered in a sintering furnace or other suitable sintering device to produce the sintered, high density, nontoxic shot.
Implementation Method 2
The green balls are then sized, tumbled, and/or mechanically agitated in any suitable device to provide precise control over the size and sphericity of the shot.
Data Source
AI summary
High density, nontoxic projectiles and other articles, and their methods of manufacture, are disclosed. More particularly, high density nontoxic W—Cu—Ni—Fe alloy compositions, methods of their manufacture and methods by which they may be used as projectiles such as shots, bullets, and pellets and other products traditionally made of lead alloys will be detailed herein in some embodiments. These products have a density comparable to that of lead while avoiding problems of toxicity associated with the use of lead.